PATENT DOCUMENT

Publication Number: US-10149396-B2
Application Number: US-201615267067-A
Country: US
Kind Code: B2

Title: Circuit assembly for an electronic device

Abstract:
Embodiments relate to systems and methods for forming a circuit assembly for an electronic device. The circuit assembly may include a substrate and a group of surface-mounted electronic components disposed on a surface of the substrate. An electrical connector may be disposed on the surface and may be configured to receive an electrical connection from a separate electrical component or assembly. A molded layer may be formed over at least a portion of the surface fully encapsulating the group of surface-mounted electronic components and partially encapsulating the electrical connector.

Claims:
What is claimed is: 
     
       1. A mobile phone comprising:
 a circuit assembly comprising:
 a substrate; 
 a group of electronic components disposed on a surface of the substrate; 
 an electrical connector disposed on the surface; and 
 a molded layer formed over at least a portion of the surface, fully encapsulating the group of electronic components, and partially encapsulating the electrical connector; and 
 
 a housing component comprising:
 a display electrically coupled to the circuit assembly via the electrical connector; and 
 a touch sensor electrically coupled to the circuit assembly via the electrical connector. 
 
 
     
     
       2. The mobile phone of  claim 1 , wherein:
 the electrical connector is configured to receive the electrical connection at an end portion; and 
 the end portion is at least partially exposed from the molded layer. 
 
     
     
       3. The mobile phone of  claim 2 , wherein:
 the end portion of the electrical connector includes a substantially flat end surface; and 
 the end surface is approximately flush with an exterior surface of the molded layer. 
 
     
     
       4. The mobile phone of  claim 1 , wherein the electrical connector is surrounded by the molded layer on four sides. 
     
     
       5. The mobile phone of  claim 1 , wherein the molded layer is formed from a thermoset polymer. 
     
     
       6. The mobile phone of  claim 1 , wherein:
 the electrical connector includes an opening for receiving an electrical connection from a separate component; and 
 the opening is substantially parallel to the surface of the substrate. 
 
     
     
       7. The mobile phone of  claim 1 , wherein:
 the electrical connector includes an opening for receiving an electrical connection from a separate component; and 
 the opening is substantially perpendicular to the surface of the substrate. 
 
     
     
       8. The mobile phone of  claim 1 , wherein the substrate comprises a silicon sheet. 
     
     
       9. The mobile phone of  claim 1 , wherein:
 the circuit assembly is a main logic board of the mobile phone; and 
 the group of components includes a computer processor. 
 
     
     
       10. The mobile phone of  claim 1 , wherein the electrical connector is:
 a zero insertion force (ZIF) connector that is configured to receive a flexible conduit; or 
 a board-to-board electrical connector for receiving an electrical connection from the display and the touch sensor. 
 
     
     
       11. The mobile phone of  claim 1 , wherein:
 the housing component further comprises a transparent cover; and 
 the display and the touch sensor are coupled to the transparent cover. 
 
     
     
       12. The mobile phone of  claim 1 , wherein the housing component is positioned above the circuit assembly. 
     
     
       13. An electronic device, comprising:
 a first circuit assembly comprising:
 a substrate; 
 an encapsulation layer positioned on the substrate; 
 an electronic component attached to the substrate and encapsulated by the encapsulation layer; and 
 an electrical connector attached to the substrate and only partially encapsulated by the encapsulation layer; and 
 
 a second circuit assembly coupled to a transparent cover layer of a housing and comprising a display electrically coupled to the first circuit assembly via the electrical connector. 
 
     
     
       14. The electronic device of  claim 13 , wherein the electrical connector and the encapsulation layer define a continuous surface. 
     
     
       15. The electronic device of  claim 13 , wherein a first end of the electrical connector is attached to the substrate and a second end of the electrical connector opposite the first end is not encapsulated by the encapsulation layer. 
     
     
       16. The electronic device of  claim 13 , further comprising a touch sensor coupled to the substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a nonprovisional patent application of U.S. Patent Application No. 62/235,355, filed Sep. 30, 2015 and titled “Circuit Assembly for an Electronic Device,” the disclosure of which is hereby incorporated herein by reference in its entirety. 
     FIELD 
     The described embodiments relate generally to electronic devices. More particularly, the present embodiments relate to a circuit assembly having a molded layer that embeds or encapsulates various components. 
     BACKGROUND 
     There is an increasing demand for electronic devices that are both compact and durable. However, in many cases, the minimum size of the device may be determined, at least in part, by the layout and packaging constraints of traditional electronic circuit assembly techniques. Using some traditional circuit board construction techniques, further reduction in the size of the electronic assemblies or systems may result in a reduction in the functionality and/or the reliability of the device. Thus, there is a need for systems and techniques that reduce the size of electronic assemblies without limiting functionality or reducing the durability of the assembly. 
     SUMMARY 
     Some example embodiments are directed to a circuit assembly for an electronic device. The circuit assembly may include a substrate and a group of electronic components disposed on a surface of the substrate. An electrical connector may be disposed on the surface and configured to receive an separate electrical part, such as a conduit or mating electrical component. A molded layer may be formed over at least a portion of the surface, fully encapsulating the group of electronic components, and partially encapsulating the electrical connector. The molded layer may be formed from a thermoset polymer. and the substrate may comprise a silicon sheet. 
     In some embodiments, the electrical connector is configured to receive the electrical connection at an end portion. The end portion may be at least partially exposed from the molded layer. In some embodiments, the end portion of the electrical connector includes a substantially flat end surface. The end surface may be approximately flush with an exterior surface of the molded layer. In some embodiments, the electrical connector is surrounded by the molded layer on four sides. 
     In some embodiments, the electrical connector includes an opening for receiving an electrical connection from a separate component. The opening may be substantially parallel to the surface of the substrate. In some embodiments, the opening is not parallel to the surface of the substrate. For example, the opening may be substantially perpendicular to the surface of the substrate. 
     In some embodiments, the circuit assembly is a main logic board of an electronic device. The group of surface-mounted components may include a computer processor. The electrical connector may include one or more of: a zero insertion force (ZIF) connector that is configured to receive a flexible conduit; or a board-to-board electrical connector for receiving an electrical connection from a separate circuit assembly. 
     Some example embodiments are directed to a circuit assembly for an electronic device. The circuit assembly may include a substrate, a group of electronic components disposed on a surface of the substrate, and a wall structure disposed on the surface and defining an enclosed region. A molded layer may be formed over at least a portion of the surface. The molded layer may surround a perimeter of the wall structure, and the molded layer may fully encapsulate the group of electronic components. A top surface of the wall structure may be substantially flush with an exterior surface of the molded layer. In some embodiments, an electrical connector is positioned within the enclosed region of the wall structure. In some embodiments, an environmental sensor is positioned within the enclosed region of the wall structure. 
     Some example embodiments are directed to a method of forming a circuit assembly for an electronic device. A group of components may be attached to a surface of a substrate. An electrical connector may be attached to the surface of the substrate. A molded layer may be formed over at least a portion of the surface to fully encapsulate the group of components and partially encapsulate the electrical connector. In some embodiments, the group of components are attached using a solder connection. 
     In some embodiments, the molded layer is formed by: placing a mold in contact with the surface of the substrate to define a mold cavity; and filling the mold cavity with a molding material to form the molded layer. 
     In some embodiments, the mold includes a protrusion that is configured to be inserted into an opening of the electrical connector. The protrusion and a surrounding region of the mold may form a seal against an end portion of the electrical connector. In some embodiments, a compliant film is disposed over at least a portion of the mold that defines the mold cavity. The compliant film may form a seal against an end portion of the electrical connector. In some embodiments, a removable plug is inserted into an opening of the electrical connector. The removable plug may prevent molding material from entering the opening while forming the molded layer. 
     In some embodiments, the electrical connector includes an opening for receiving an electrical connection from a separate component. The opening may be substantially parallel to the first side of the substrate. In some embodiments, the opening is not parallel or is at an angle with respect to the surface of the substrate. For example, the opening may be substantially perpendicular to the first side of the substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  depicts an exploded view of an example electronic device having a circuit assembly; 
         FIG. 2  depicts an example circuit assembly having a molded layer; 
         FIG. 3  depicts a cross-sectional view of the circuit assembly of  FIG. 2 ; 
         FIGS. 4A-4C  depict cross-sectional views of example molding techniques for forming the circuit assembly of  FIGS. 2 and 3 ; 
         FIGS. 5A-5C  depict cross-sectional views of example molding techniques for forming an alternative circuit assembly; and 
         FIG. 6  depicts an example circuit assembly having an internal region formed within a molded layer. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     Electronic devices typically include one or more circuit assemblies configured to provide associated functionality. A circuit assembly may include a substrate, such as a printed circuit board, and a group of electronic components that are electrically and structurally coupled to a surface of the substrate. The circuit assembly may include one or more processing units, controllers, or other integrated circuits that are configured to control various aspects of the electronic device. The circuit assembly may also include components for performing various communication functionality including, for example, wireless transceivers, antennas, and specialized communication integrated circuits. 
     Using traditional circuit assembly techniques, the layout and spacing of the components may be constrained by the size of the bonding areas, which may provide both the electrical and structural connections between the various electronic components and the substrate. Additionally, some traditional circuit assemblies include exposed elements that may be vulnerable to moisture or other contaminants. 
     Some embodiments described herein are directed to a circuit assembly that includes a molded layer that encapsulates or embeds a group of electronic components within the molded material. The molded layer may provide structural support for the electronic components, which may reduce the minimum size of bonding or mounting areas for some of the components. In some instances, the use of a molded layer may allow for the components to be more tightly spaced, resulting in a more compact circuit assembly. The molded layer may also function as a protective barrier and protect the electronic components from exposure to moisture and other potential contaminants. 
     Using a molded layer may, however, present various challenges. For example, in order to include an electrical connector on the circuit assembly, it may be necessary to increase overall size of the substrate. For example, the substrate may be increased in length or width to accommodate an un-molded region along the edge of the substrate for mounting the connector. The size of the substrate may need to be further increased to allow for the placement of tooling (e.g., a mold chase) during the molding process in order to avoid potential interference between the tooling and any electrical connectors positioned along an edge of the substrate. 
     Some embodiments described herein are directed to systems and techniques for integrating an electrical connector within the molded layer of a circuit assembly. In particular, some embodiments are directed to processes for forming a molded layer that fully encapsulates the electronic components but only partially encapsulates the electrical connector. This may be achieved, for example, by forming multiple parting lines when forming the molded layer. A first interior parting line may be formed between the mold and the electrical connector, and a second parting line may be formed between the mold and the substrate of the circuitry assembly. In some cases, an end portion of the electrical connector remains exposed after the molding process in order to facilitate electrical connection with other components or assemblies. 
     These and other embodiments are discussed below with reference to  FIGS. 1-6 . However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these Figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  depicts an example electronic device that includes a circuit assembly having a molded layer in accordance with some embodiments. In the present example, the electronic device  100  is a portable electronic device, such as a mobile phone. The embodiments described herein may also be applicable to a broad range of other electronic devices including, for example, tablet computing devices, notebook computing devices, desktop computing devices, portable media player devices, wearable electronic devices, health monitoring devices, and so on. 
     In the present example, the electronic device  100  includes a circuit assembly  110  that is positioned within a housing  101   a ,  101   b . The circuit assembly  110  may be operatively coupled to various components of the electronic device  100  and may function as a main logic board or main controller for the device  100 . In the present example, the circuit assembly  110  is operatively coupled to a display  102  and a touch sensor  103  positioned within or integrated with a top portion of the housing  101   b . The circuit assembly  110  may also be operatively coupled to an internal power source, such as a battery. Other components including, for example, a speaker, a microphone, a button, a biosensor, a light source, and/or a camera may also be operatively coupled to the circuit assembly  110 . While  FIG. 1  depicts an electronic device  100  having a single circuit assembly  110 , some implementations may include multiple circuit assemblies that are interconnected with each other and with the other various components of the electronic device  100 . 
     The various components of the electronic device  100  may be coupled to the circuit assembly  110  using one or more electrical connections. As shown in  FIG. 1 , the circuit assembly  110  includes an electrical connector  112 , which may be used to couple or connect the components of the electronic device  100  to the circuit assembly  110 . While a single representative electrical connector  112  is depicted, the circuit assembly  110  may include multiple electrical connectors  112  depending on the implementation. 
     The electrical connector  112  may be configured to receive an electrical conduit, such as a flexible conduit or terminated wire bundle. In some implementations, the electrical connector  112  includes a zero-insertion force (ZIF) connector that is configured to receive a flexible circuit or conduit. The electrical connector  112  may also be configured to receive a board-to-board electrical connector that is attached to a separate circuit assembly or electrical component. Use of an electrical connector  112  may facilitate electrical connection using a removable or relatively serviceable electrical coupling, which may be advantageous over other more permanent electrical coupling techniques, such as soldering or reflowing techniques. 
     As shown in the exploded view of  FIG. 1 , the circuit assembly  110  is positioned within a housing formed from a top portion  101   b  and a bottom portion  101   a  that together form the exterior surface of the device  100 . The top portion  101   b  may include a cover formed from a hard transparent material, such as glass, sapphire, or other ceramic. The cover may also be formed from a polymer, such as polycarbonate, acrylic, or other material. The top portion  101   b  may be joined to the bottom portion  101   a  to form an enclosed volume. The top portion  101   b  may be attached to the bottom portion  101   a  using an adhesive, mechanical joint, or other fastening technique. While  FIG. 1  depicts the housing as a two-piece housing formed from top  101   b  and bottom  101   a  portions, in other embodiments, the housing may be formed from a single piece in which the circuit assembly  110  is inserted or installed. Likewise, the housing may be formed from more than two pieces that together define the exterior surface of the device  100 . 
       FIG. 2  depicts an example circuit assembly having a molded layer. The circuit assembly  110  may be used as a main logic board or other electrical system of an electronic device, as described above with respect to  FIG. 1 . The circuit assembly  110  may also be used as a control board for one or more hardware components, such as a display, touch sensor, biosensor module, digital camera module, or other hardware subsystem. 
     As shown in  FIG. 2  the circuit assembly includes a substrate  111 , which may be formed from substantially rigid material, such as phenolic, fiberglass, epoxy, or other similar material. In some embodiments, the substrate  111  may be formed from a semiconductor, such as silicon, germanium, or other semiconductor materials. The semiconductor may be formed as a sheet or as a substantially flat and thin portion of material. The substrate  111  may include one or more layers of electrical traces formed within the material that are configured to make electrical connections between various components of the circuit assembly  110 . In some embodiments, the substrate  111  may be formed from or include a flexible or semi-rigid material, such as a polymer sheet or other flexible plastic substrate. 
     A group of electronic components  116  may be disposed on a surface of the substrate  111 . In the present example, multiple electronic components  116  are disposed on a single (upper) side of the substrate  111 . In other embodiments, both sides of the substrate  111  may be used to mount or attach electronic components. The electronic components  116  may be attached using a technique that provides both an electrical connection and a structural connection to the substrate  111 . For example, the electronic components  116  may be attached to the substrate  111  using a solder connection or other electrically conductive attachment technique. In some embodiments, the electronic components  116  include one or more surface-mounted components that are configured to be attached using a surface-mount technology (SMT). For example, the electronic components  116  may include components that are configured to be mated directly to the surface of the substrate  111 . The electronic components  116  may also be attached using an adhesive, mechanical fastener, or other securing technique. 
     The electronic components  116  may include a wide range of electronic components. For example, the electronic components  116  may include various types of passive components, including resistors, capacitors, inductors, and the like. The electronic components  116  may also include various types of integrated circuit (IC) components, radio-frequency (RF) or wireless components, discrete semiconductor components, light emitting diode components, and the like. The electronic components  116  may also include one or more computer processors, controllers, application-specific integrated circuits (ASICS), and the like. Other electronic components  116  include sensors, such as accelerometers, gyroscopes, temperature sensors, barometer sensors, magnetic field sensors, and the like. Broadly, electronic components may also include electromechanical components that may be attached to the substrate  111  or otherwise integrated with the circuit assembly  110 . Example electromechanical components include thermal heat sinks, stiffeners, mechanical fasteners, shields, microelectromechanical systems (MEMS), and the like. 
     In the present embodiment, a group of the electronic components  116  are fully encapsulated or embedded within a molded layer  114 . For example, at least a subset of the electronic components  116  may be completely surrounded and fixed within the molded layer  114 . It is not necessary that all of the electronic components  116  be fully encapsulated within the molded layer  114 . In fact,  FIG. 6  depicts an example in which at least a subset of the electronic components remains exposed after the molded layer has been formed. 
     The molded layer  114  may provide structural support for the electronic components  116  and help to maintain the structural (and electrical) connection between the electronic components  116  and the substrate  111 . The molded layer  114  may also form a protective barrier around the electronic components  116  and prevent exposure to moisture, liquid, and other potential contaminants. The molded layer  114  may also reduce the risk of damage caused by a physical impact or other form of mechanical shock. 
     The molded layer  114  may substantially cover the upper surface of the substrate  111 . In the present example, the molded layer  114  covers all of the upper surface except for a boundary portion  115 . The boundary portion  115  may correspond to the amount of substrate that remains exposed after the molded layer  114  has been formed. The boundary portion  115  may be used to form a mold seal or parting line, as discussed in more detail with respect to  FIGS. 4A-4C and 5A-5C . The boundary portion  115  may also facilitate handling of the circuit assembly  110  by providing a datum edge or feature that can be used to fixture or register the circuit assembly  110 . 
     As shown in  FIG. 2 , the circuit assembly  110  also includes an electrical connector  112 , which may be partially encapsulated or embedded within the molded layer  114 . The electrical connector  112  may include an opening or receptacle that is configured to receive an electrical connection from a separate component or circuit assembly. In the present embodiment, an end portion of the electrical connector is at least partially exposed from the molded layer  114 . In some cases, the end portion of the electrical connector  112  includes a substantially flat end surface, which may be approximately flush with the exterior surface of the molded layer  114 . By keeping at least a portion of the electrical connector  112  exposed, the circuit assembly  110  may be electrically connected to other components within the device using a removable or relatively serviceable electrical coupling. The electrical connector  112  may be, for example, an existing surface-mount technology connector component that is configured to removably engage a separate connecting electrical component or conduit. 
       FIG. 3  depicts a cross-sectional view of the circuit assembly of  FIG. 2 . As shown in  FIG. 3 , the circuit assembly  110  includes a molded layer  114  formed on an upper surface of the substrate  111 . The circuit assembly  110  also includes multiple electronic components  116   a - f  that are fully or completely encapsulated within the molded layer  114 . The electronic components  116   a - f  may include a variety of electrical and electromechanical components, as described above with respect to  FIG. 2 . A perimeter or boundary portion  115  of the substrate  111  may remain exposed after the molded layer  114  has been formed. 
     As shown in  FIG. 3 , the electrical connector  112  is only partially encapsulated by the molded layer  114 . In the present embodiment, the electrical connector  112  is surrounded on four sides by the molded layer  114 . An end portion of the electrical connector  112  having a flat end surface remains exposed after the molded layer  114  has been formed. As shown in  FIG. 3 , the flat end surface of the electrical connector  112  is substantially flush with an upper, exterior surface of the molded layer  114 . In some embodiments, the electrical connector  112  may be slightly raised or protrude with respect to the exterior surface of the molded layer  114 . The electrical connector  112  may also be recessed with respect to the exterior surface of the molded layer  114 . 
       FIGS. 4A-4C  depict cross-sectional views of example molding techniques for forming a circuit assembly, such as the circuit assembly  110  of  FIGS. 2 and 3 . In particular,  FIGS. 4A-4C  depict an example molding process that may be used to form the molded layer of the circuit assembly. The examples of  FIGS. 4A-4C  may represent a compression molding process, a transfer molding process, an injection molding process, or other similar molding process used to receive a liquid form of a material into a mold and form a solid part having a shape that corresponds to the shape of the mold. 
       FIG. 4A  depicts an example mold  400  for forming the molded layer  114  of a circuit assembly  110  in accordance with various embodiments described herein. The example of  FIG. 4A  depicts the molded layer  114  after being formed into a solid part using the mold  400 . In the example of  FIG. 4A , the mold  400  includes a lower mold  404  and an upper mold  402 , which together with the substrate  111  define a mold cavity. In the present embodiment, the upper mold  402  is configured to contact and form a seal against the boundary portion  115  of the substrate  111 . In an alternative embodiment, the upper mold  402  may be configured to contact and form a seal against a portion of the lower mold  404 . The seal between the upper mold  402  and the substrate  111  (or alternatively between the upper mold  402  and the lower mold  404 ) forms an exterior or peripheral parting line of the mold  400 . The interface at the parting line may be configured to prevent leakage or flashing of the molding material during the molding operation. 
     The upper mold  402  also includes a protrusion  406  that is configured to be at least partially inserted into an opening or receptacle of the electrical connector  112 . It is not necessary, and in some cases not desirable, that the protrusion  406  be fully inserted within the electrical connector  112 . The protrusion  406  and the surrounding region of the upper mold  402  are configured to contact and form a seal against the upper or end portion of the electrical connector  112 . The seal between the protrusion  406 , surrounding region of the upper mold  402 , and the electrical connector  112  may form an internal parting line. Similar to the external or peripheral parting line, the interface at the internal parting line may be configured to prevent leakage or flashing of the molding material during the molding operation. The insertion of the protrusion  406  into the opening of the electrical connector  112  may reduce the potential for flashing or leakage into the electrical connector  112 . 
     In general, it may be advantageous to control the tolerance between the components that form both the external and internal parting line of the mold. In particular, the overall flatness of the boundary portion  115  of the substrate  111  should be maintained with respect to the electrical connector  112 . The height of the electrical connector  112  and the thickness of any mounting medium (e.g., solder or adhesive) may be controlled to provide a consistent height difference between the top surface of the boundary portion  115  and the end surface of the electrical connector  112 . In some embodiments, an assembly fixture is used to position the electrical connector  112  to a height that facilitates the formation of a reliable parting line during the molding operation. In some embodiments, the end surface of the electrical connector  112  may be machined or ground to achieve the desired height. In some implementations, a compliant material or gasket is integrally formed on the end of the electrical connector  112 , which may provide enough compliance to accommodate variations in tolerance between the various components. 
     When the upper mold  402  and lower mold  404  are brought together, the mold cavity may be substantially enclosed and sealed (except for one or more injection ports or other liquid-delivery passages). A liquid form of the molding material may be introduced to the mold cavity using a pressure or gravity feed delivery system. The liquid form of the material may be in a melted or uncured state and have a viscosity sufficiently low to enable the liquid to fill the entire mold cavity. In some cases, pressure and/or a vacuum is used to force or draw air out of the mold cavity during the filling operation. 
     In some embodiments, a progressive pressure is applied to the liquid as the molded layer  114  is being formed. For example, the pressure of the liquid material in the mold may be progressively increased in accordance with a progressively increasing clamp pressure exerted between the upper and lower molds  402 ,  404 . The application of a progressive pressure profile over a molding operation may facilitate higher clamping forces without crushing or damaging components of the circuit assembly  110 , particularly the electrical connector  112 . 
     Once the mold cavity has been filled, the liquid form of the material may be cooled and/or cured to form a solid molded layer  114 . In some embodiments, one or both of the upper and lower molds  402 ,  404  include heating and/or cooling elements that may be controlled to facilitate a filling, curing, and/or cooling operation. Once the solid molded layer has been cured or cooled, the upper and lower molds  402 ,  404  may be separated and the circuit assembly  110  may be removed. As shown in  FIG. 4A , one or more surfaces of the upper mold  402  may be drafted or tapered to facilitate removal of the circuit assembly  110  after the molded layer  114  has been formed. 
     The mold  400  may be used to form the molded layer  114  from a variety of different materials. In some embodiments, the molded layer  114  may be formed from a thermoset polymer, such as a polyurethane, polyester, polyimide, resin, or other similar material. In some embodiments, the molded layer may be formed from a thermoplastic polymer, such as a polycarbonate, polyethylene, nylon, acrylic, acrylonitrile butadiene styrene (ABS), or other similar material. In general, it may be beneficial to use a material that can be molded in a process that does not require temperatures that could damage the electronic components of the circuit assembly  110 . 
       FIG. 4B  depicts an example mold  420  for forming the molded layer  114  of a circuit assembly  110  in accordance with various embodiments described herein. In the example of  FIG. 4B , the mold  420  includes a lower mold  404  and an upper mold  422 , which together with the substrate  111  define a mold cavity. Similar to the previous example, the upper mold  422  is configured to contact and form a seal against the boundary portion  115  of the substrate  111 . In an alternative embodiment, the upper mold  422  may be configured to contact and form a seal against a portion of the lower mold  404 . The seal between the upper mold  422  and the substrate  111  (or alternatively between the upper mold  422  and the lower mold  404 ) form an exterior or peripheral parting line of the mold  420 , which may be configured to prevent leakage or flashing of the molding material during the molding operation. 
     Similar to the previous example, the upper mold  422  is also configured to contact and form a seal against the upper or end portion of the electrical connector  112  to form an internal parting line. Similar to the external or peripheral parting line, the interface at the internal parting line may be configured to prevent leakage or flashing of the molding material during the molding operation. 
     To facilitate the formation of an internal and external parting line, a compliant film  424  may be disposed between a surface of the upper mold  422  and the mating surfaces, such as between the boundary portion  115  and the end surface of the electrical connector  112 . The compliant film  424  may accommodate some amount of dimensional variation between the various components of the system to facilitate a consistent and reliable internal and external parting line. In particular, the compliant film  424  may accommodate some variation in height of the end surface of the electrical connector  112  with respect to the boundary portion  115 . The compliant film  424  may also facilitate the formation of a seal by conforming to local surface irregularities along the boundary portion  115  and/or the electrical connector  112 . 
     The compliant film  424  may be formed from a polymer film such as polyester Mylar, Polyimide Kapton, polyester PEN, and other similar materials. In some embodiments, the compliant film  424  has a thickness less than 1 mm. In some cases, the compliant film  424  has a thickness of approximately 0.1 mm. The compliant film  424  may include an adhesive or bonding layer to facilitate installation into mold  420 . 
       FIG. 4C  depicts an example mold  430  for forming the molded layer  114  of a circuit assembly  110  in accordance with various embodiments described herein. In the example of  FIG. 4C , the mold  430  includes a lower mold  404  and an upper mold  432 , which together with the substrate  111  define a mold cavity. Similar to the previous examples, the upper mold  432  is configured to contact and form a seal against the boundary portion  115  of the substrate  111  to form an exterior or peripheral parting line of the mold  430 , which may be configured to prevent leakage or flashing of the molding material during the molding operation. 
     An internal parting line may be formed around the electrical connector  112  by using a removable plug  434 . The removable plug  434  may be inserted into an opening of the electrical connector  112  prior to molding. The removable plug  434  may be configured to prevent the (liquid) mold material from entering the opening while forming the molded layer  114 . The removable plug  434  may be formed from a compliant material to facilitate the formation of both an internal and external parting line. In particular, the removable plug  434  may accommodate variations in height between the substrate  111  of the circuit assembly  110  and the end surface of the electrical connector  112 . 
     Additionally, the removable plug  434  may remain inserted into the electrical connector  112  after molding in order to prevent foreign contaminants from entering the electrical connector  112 . In some cases, the removable plug  434  forms a moisture-proof barrier to prevent liquid, water vapor, or other moisture from entering the electrical connector  112 . The removable plug  434  may remain inserted into the electrical connector  112  until the circuit assembly  110  is being installed in the electronic device. 
       FIGS. 5A-5C  depict cross-sectional views of example molding techniques for forming an alternative circuit assembly. In the examples of  FIGS. 5A-5C , the electrical connector  512  is mounted along an edge of the substrate  511  in an orientation that is at an angle with respect to (e.g., substantially perpendicular to) the examples of  FIGS. 4A-4C . In particular, in the examples of  FIGS. 4A-4C  the electrical connector  112  is positioned such that the opening for receiving the electrical connection is substantially parallel to the upper surface of the substrate  111 . This configuration may be referred to as an end-mounted connector. In contrast, in the examples of  FIGS. 5A-5C , an electrical connector  512  is positioned such that the opening for receiving the electrical connection is at an angle with respect to (e.g., substantially perpendicular to) the upper surface of the substrate  511 . This configuration may be referred to as a side-mounted connector. 
       FIG. 5A  depicts an example mold  500  for forming a circuit assembly  510  having a side-mounted electrical connector  512 . In this example, the electrical connector  512  is positioned along an edge of the substrate  511  of the circuit assembly  510 . While the electrical connector  512  is depicted as being offset or recessed with respect to an edge of the substrate  511 , in other examples, the electrical connector  512  may be flush or extend beyond the edge of the substrate  511 . 
     Similar to the previous examples, the mold  500  includes an upper mold  502  and a lower mold  504  that, along with the circuit assembly  510 , are configured to define a mold cavity used to form the molded layer  514 . In this example a first parting line is formed between the upper mold  502  and the substrate  511 . The first parting line is formed around the perimeter or outside edges of the substrate  511  similar to the previous examples. A second parting line is formed between a side wall of the upper mold  502  and the end surface of the electrical connector  512 . 
     To facilitate sealing and prevent leakage or flashing at both parting lines, a compliant film  506  may be used as shown in  FIG. 5A . In particular, a compliant film  506  may be disposed between one or more surfaces of the upper mold  502  and the substrate  511  and the electrical connector  512 . As described previously with respect to  FIG. 4B , the compliant film  506  may accommodate variations in dimensions or tolerances between the components to facilitate reliable parting lines within the mold  500 . The materials used for the compliant film  506  are similar to those described above with respect to  FIG. 4B . 
       FIG. 5B  depicts an example mold  520  for forming a circuit assembly  510  having a side-mounted electrical connector  512  that is positioned along an edge of the substrate  511  of the circuit assembly  510 . Similar to the previous examples, the mold  520  includes an upper mold  522  and a lower mold  504  that, along with the circuit assembly  510 , are configured to define a mold cavity used to form the molded layer  514 . 
     Similar to the example of  FIG. 4C , the embodiment of  FIG. 5B  includes a removable plug  524  that is inserted at least partially within an opening or receptacle of the electrical connector  512 . In this example a first parting line is formed between the upper mold  522  and the substrate  511 . A second parting line is formed between a side wall of the upper mold  522  and the removable plug  524 . Similar to the previous example, the removable plug  524  may be formed from a compliant material, which may accommodate variations in dimensions or tolerances between the components to facilitate reliable parting lines within the mold  520 . Also similar to the previous example, the removable plug  524  may remain installed or inserted after molding to protect internal contacts or components of the electrical connector  512 . 
       FIG. 5C  depicts an example mold  530  for forming a circuit assembly  510  having a side-mounted electrical connector  512  that is positioned along an edge of the substrate  511  of the circuit assembly  510 . Similar to the previous examples, the mold  530  includes an upper mold  532  and a lower mold  504  that, along with the circuit assembly  510 , are configured to define a mold cavity used to form the molded layer  514 . 
     In the present example, a side-action insert  534  may be inserted into an opening of the electrical connector  512  to prevent molding material from entering the electrical connector  512  during the molding process. The insertion of the side-action insert  534  may be coordinated with the closing of the upper mold  532  with respect to the lower mold  504 . The insertion of the side-action insert  534  may be mechanically linked to the motion of the upper and lower molds  532 ,  504 . In some cases, the insertion of the side-action insert  534  is performed by a separate actuator or drive system. 
     Similar to the previous examples, a first parting line may be formed between the upper mold  532  and the substrate  511  of the circuit assembly  510 . A second parting line may be formed between the upper mold  532  and the side-action insert  534  to seal the opening of the electrical connector  512 . The seal or parting line between the upper mold  532  and the side-action insert  534  may be adjusted or maintained by controlling the insertion distance of the side-action insert  534 . For example, the side-action insert  534  may include a taper or draft that is configured to mate with a corresponding taper or draft on the upper mold  532 . Inserting the side-action insert  534  further into the mold cavity may decrease the gap or take up any clearance between the two components due to the mating tapers or drafts. Thus, the side-action insert  534  may provide an active measure for accommodating for variations in dimensions between the components. 
     In general, the system and techniques described above with respect to  FIGS. 4A-4C and 5A-5C  may be used to form a molded layer having two parting lines. By forming an internal parting line, an interior region of the molded layer may remain exposed or unmolded, which may be advantageous for providing access to an embedded electrical connector. Similar techniques may also be applied to other constructions to define an internal, un-molded region within the circuit assembly that can be used to mount various types of components. 
       FIG. 6  depicts an example circuit assembly  610  having an internal region formed within a molded layer. In the present example, a wall structure  612  may be used to define an enclosed region which is surrounded by the molded layer  614 . Various components  624  may be positioned within the enclosed region, as depicted in  FIG. 6 . 
     In the example of  FIG. 6 , the wall structure  612  may be attached to or otherwise disposed on a surface of a substrate  611 . A group of electronic components  616  may also be disposed on the same surface of the substrate  511 . The wall structure  612  and/or the electronic components  616 ,  622 ,  624  may be attached using surface mount technology, in accordance with other examples provided herein. 
     Similar to the previous examples, a molded layer  614  may fully or completely encapsulate the group of electronic components  616 . The molded layer  614  may also surround a perimeter of the wall structure  612  to partially encapsulate the wall structure  612 . As shown in  FIG. 6 , the interior volume defined by the wall structure  612  may be unmolded or otherwise not encapsulated by the molded layer  614 . 
     Any one of the molding techniques described above with respect to  FIGS. 4A-4C  may be used to form the unmolded, interior volume depicted in  FIG. 6 . In particular, an internal parting line may be formed between an upper mold and an upper surface of the wall structure  612 . As shown in  FIG. 6 , the upper surface of the wall structure  612  is substantially flush with an upper, exterior surface of the molded layer  614 . Similar to previous examples, an external parting line may also be formed between the upper mold and the upper surface of the substrate  611 . To facilitate formation of two parting lines, a protrusion similar to as described with respect to  FIG. 4A  may be used. Similarly, the compliant film of  FIG. 4B  and the removable plug of  FIG. 4C  may also be used to form the two parting lines. 
     The formation of an enclosed volume may be advantageous for mounting various components. As shown in  FIG. 6 , an electrical connector  622  may be positioned within the enclosed volume, which may provide access to one or more sides of the electrical connector  622 . This may be advantageous if the electrical connector  622  is a zero-insertion force (ZIF) connector having a clamp or release mechanism located along the side or base of the connector. In some embodiments, the wall structure  612  is offset from the electrical connector  622  with just enough space to access the clamp or release mechanism with a thin tool. 
     In some embodiments, other components  624 , such as an environmental sensor, may be positioned within the enclosed region of the wall structure  612 . Exposure to environmental conditions may be important or critical to the operation of various environmental sensors, such as barometric sensors, moisture sensors, humidity sensors, ambient temperature sensors, and the like. Other components  624  may also include field-serviceable components or adjustable components, such as adjustable potentiometers, that may require direct physical interaction during normal operation or servicing. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20160915
Publication Date: 20181204
Grant Date: 20181204
Priority Date: 20150930
Inventors: LOR, JASON
GOOCH, SCOTT L.
NANGIA, SIDDHARTH
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1327", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1316", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/10189", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1327", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 58407726