PATENT DOCUMENT

Publication Number: US-11266010-B2
Application Number: US-201916720666-A
Country: US
Kind Code: B2

Title: Multi-layer thin-film coatings for system-in-package assemblies in portable electronic devices

Abstract:
A portable electronic device packaged into a System-in-Package assembly is disclosed. The portable electronic device can include a substrate and a plurality of components mounted on the substrate and included in one or more subsystems. Interference between subsystems or from external sources can be reduced or eliminated by disposing an insulating layer over the components, forming narrow trenches between subsystems, and depositing one or more layers of a multi-layer thin film stack on the insulating layer and filling the trenches. In some examples, the multi-layer thin film stack can include an adhesion layer, a shielding layer, a protection layer, and a cosmetic layer. In some examples, the multi-layer thin film stack can include multi-functional layers such as a protection and cosmetic layer.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a substrate; 
 a plurality of electronic components mounted on the substrate; 
 an insulating layer on the substrate and encapsulating the plurality of electronic components, wherein the insulating layer comprises a topmost surface; 
 a trench formed through the insulating layer, the trench extending from the topmost surface to the substrate to segregate the plurality of electronic components into a first subsystem including one or more of the plurality of electronic components and a second subsystem including one or more of the plurality of electronic components, the trench separating the first subsystem from the second subsystem; and 
 a shielding structure comprising:
 an electrically conductive shielding layer that substantially fills the trench; 
 a protection layer over the shielding layer and the insulating layer, wherein the protection layer is formed of a first metal or metal alloy and does not fill the trench, wherein the protection layer conformally coats outermost side surfaces of the substrate. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the substrate is a printed circuit board. 
     
     
       3. The electronic device of  claim 1 , further comprising an adhesion layer underneath the protection layer. 
     
     
       4. The electronic device of  claim 3 , wherein the adhesion layer conformally coats the outermost side surfaces of the substrate. 
     
     
       5. The electronic device of  claim 4 , wherein the adhesion layer is formed of a second metal or metal alloy. 
     
     
       6. The electronic device of  claim 5 , wherein the adhesion layer is formed of stainless steel. 
     
     
       7. The electronic device of  claim 6 , wherein the electrically conductive shielding layer comprises copper. 
     
     
       8. The electronic device of  claim 7 , wherein the first metal or metal alloy is selected from the group consisting of stainless steel, gold, and platinum. 
     
     
       9. The electronic device of  claim 5 , wherein the insulating layer comprises an over-molding material. 
     
     
       10. The electronic device of  claim 9 , wherein the over-molding material comprises epoxy. 
     
     
       11. The electronic device of  claim 9 , wherein the substrate comprises a ground plane, and a metal trace coupled to the ground plane. 
     
     
       12. The electronic device of  claim 11 , wherein the shielding structure is electrically connected to the metal trace. 
     
     
       13. The electronic device of  claim 12 , wherein the electrically conductive shielding layer within the trench is on and electrically connected to the metal trace. 
     
     
       14. The electronic device of  claim 13 , wherein the electrically conductive shielding layer is thicker than the protection layer. 
     
     
       15. The electronic device of  claim 14 , further comprising a second adhesion layer over the protection layer. 
     
     
       16. The electronic device of  claim 15 , wherein the second adhesion layer conformally coats the outermost side surfaces of the substrate. 
     
     
       17. The electronic device of  claim 16 , further comprising a cosmetic layer over the second adhesion layer. 
     
     
       18. The electronic device of  claim 15 , wherein the cosmetic layer conformally coats the outermost side surfaces of the substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of co-pending U.S. patent application Ser. No. 15/935,899, filed Mar. 26, 2018, which is a continuation of U.S. patent application Ser. No. 14/308,463, filed Jun. 18, 2014 now issued as U.S. Pat. No. 9,949,359, which claims the benefit under 35 USC 119(e) of U.S. Patent Application No. 61/955,063, filed Mar. 18, 2014, the contents of which are incorporated herein by reference in their entirety for all purposes. 
    
    
     FIELD 
     This relates generally to mitigating interference and, more particularly, to thin film coatings to help provide electromagnetic shielding, adhesion to underlying layers, enhanced aesthetic appeal, and resistance to degradation or discoloration in System-In-Package assemblies in compact portable electronic devices. 
     BACKGROUND 
     Compact portable electronic devices are becoming increasingly popular. Examples of compact portable electronic devices include laptop computers, tablet computing devices, cellular telephones, media players, gaming devices, handheld devices, miniature devices such as pendant and wearable devices, and other devices. It is generally desirable to reduce both internal and external interference of the components in the compact portable electronic devices. The interference can be reduced or eliminated using electromagnetic shielding. For example, some electronic devices include radio-frequency transceiver circuits that are susceptible to radio-frequency interference. Electronic devices can also include memory and other components that use clock signals during normal operation. If care is not taken, signals from one circuit can interfere with the proper operation of another circuit. For example, a clock signal or a clock signal harmonic that falls within the operating band of a radio-frequency receiver can cause undesirable interference for a radio-frequency transceiver. 
     To protect devices from electromagnetic interference, circuits such as radio-frequency transceivers can be enclosed within metal shielding cans, or a conductive paste can be disposed between the circuits. The metal of the shielding cans or the conductive paste can block signals and can help shield the enclosed components from electromagnetic interference. To reduce the size of compact portable electronic devices, the circuitry can be integrated into a System-in-Package. However, shielding cans and conductive paste can limit the effectiveness of the shielding and can limit the size of the device. An alternative to the metal shielding cans and conductive paste are thin-film metal layers. However, the thin-film metal layers can have limited shielding effectiveness, poor adhesion to underlying layers, can be aesthetically unappealing, and can be susceptible to environment-induced degradation or discoloration. 
     SUMMARY 
     This relates to a compact portable electronic device and multi-layer thin-film coatings for System-in-Package assemblies. The compact portable electronic device can be assembled into a single package to reduce size and enhance form factor. Several tens or hundreds of electrical components including multiple dies, passive components, mechanical or optical components can be packaged in a single system on a printed circuit board. Components can be grouped and arranged into subsystems based on their functionality. Multi-layer thin films coatings can improve shielding effectiveness, enhance adhesion to underlying layers, enhance the aesthetic appeal, and prevent or reduce environment-induced degradation or discoloration. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1D  illustrate example systems in which examples of the disclosure can be implemented. 
         FIG. 2A  illustrates a perspective view of an exemplary portable electronic device. 
         FIG. 2B  illustrates a block diagram of an exemplary portable electronic device. 
         FIG. 2C  illustrates a block diagram of an exemplary portable electronic device. 
         FIG. 3  illustrates a perspective view of an exemplary compact portable electronic device that includes components. 
         FIG. 4  illustrates an exemplary portable electronic device with metal cans used for shielding. 
         FIG. 5  illustrates a cross-sectional view of an exemplary portable electronic device with conductive paste used for shielding. 
         FIGS. 6A-6D  illustrate cross-sectional views of an exemplary portable electronic device packaged into a System-in-Package assembly with a multi-layer thin-film stack used as shielding. 
         FIG. 6E  illustrates a flow diagram of an exemplary process for forming an exemplary portable electronic device. 
         FIG. 7A  illustrates a cross-sectional view of an exemplary portable electronic device packaged into a System-in-Package assembly with a multi-layer thin-film stack used as shielding. 
         FIG. 7B  illustrates a flow diagram of an exemplary process for forming an exemplary portable electronic device. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description of examples, reference is made to the accompanying drawings in which it is shown by way of illustration specific examples that can be practiced. It is to be understood that other examples can be used and structural changes can be made without departing from the scope of the various examples. 
     This relates to multi-layer thin film coatings for electrical, mechanical, and optical components and subsystems in a portable electronic device assembled using System-in-Package (SiP) technology. The multi-layer thin film coatings can be used for radio-frequency shielding and/or magnetic shielding. The multi-layer thin film coatings can shield components such as integrated circuits that operate in radio-frequency bands (e.g., transceiver integrated circuits, memory circuits and other circuits). Components can also include circuitry formed from one or more discrete components such as inductors, capacitors, resistors, switches, etc. The components that are shielded can be aggressors (components that produce radio-frequency or magnetic shield interference) and/or victims (components that are sensitive to interference that is received from external sources). The multi-layer thin film coatings can help to reduce electromagnetic interference. Additionally, the multi-layer thin film coatings can provide enhanced adhesion to underlying layers, enhance aesthetic appeal, and prevent or eliminate environment-induced degradation or discoloration. 
     In recent years, portable electronic devices such as laptops, tablet computing devices, cellular telephones, media players, gaming devices, handheld devices, miniature devices, etc., have become small, light and powerful. One factor contributing to this reduction in size can be attributed to the manufacturer&#39;s ability to fabricate various components of these devices in smaller and smaller sizes while, in some cases, increasing the power and/or operating speed of such components. Another factor contributing to the reduction in size is that from a visual standpoint, users often find compact and sleek designs of portable electronic devices more aesthetically appealing and thus demand compact and sleek designs. The trend for smaller, lighter, more compact and powerful presents continuing challenges in the design of portable electronic devices and their associated components. 
     One area that enables small and compact devices can be internal packaging. A particular device can have a desired form factor and functionality. The desired form factor determines a size of the housing in which all of the device components that provide the desired functionality are packaged. The internal packaging design involves minimizing any unused dead space that does not contribute in some way to the functioning of the device while still fitting the needed components in an allotted space dictated by the form factor. 
     Electrical, mechanical, and optical components can be included in one or more subsystems and packaged using the System-in-Package (SiP) technology. SiP is a functional system assembled into a single package. Several tens or hundreds of components including multiple dies, passive components, and mechanical or optical components can be packaged in a single system on a printed circuit board (PCB). The PCB can be formed from rigid PCB materials such as fiberglass-filled epoxy (e.g., FR4), flexible printed circuits (e.g., printed circuits formed from flexible sheets of polymer such as polyimide), and rigid flex circuits (e.g., printed circuits that contain both rigid portions and flexible tails). PCBs on which components such as integrated circuit components and discrete components are mounted can sometimes be referred to as main logic boards (MLBs). The components can be mounted on the PCB using solder or other suitable mounting arrangements. For example, the components can be surface-mount technology (SMT) components that are mounted directly onto a PCB. SiP can lead to higher volumetric efficiency, superior reliability, higher performance, and smaller form factor. 
     PCBs having shielded components can be used in electronic devices such as desktop computers, computers built into computer monitors, television set top boxes, audio-video equipment, and portable electronic devices such as laptop computers, tablet computing devices, cellular telephones, media players, gaming devices, handheld devices, miniature devices such as pendant and wristwatch devices, or other electronic equipment. 
       FIGS. 1A-1D  illustrate systems in which examples of the disclosure can be implemented.  FIG. 1A  illustrates an exemplary mobile telephone  136  that includes a display screen  124  packaged in housing  150 .  FIG. 1B  illustrates an exemplary digital media player  140  that includes a display screen  126  packaged in housing  160 .  FIG. 1C  illustrates an exemplary personal computer  144  that includes a display screen  128  packaged in housing  170 .  FIG. 1D  illustrates an exemplary tablet computing device  148  that includes a display screen  130  packaged in housing  180 . 
       FIG. 2A  illustrates a perspective view of an exemplary portable electronic device. Portable electronic device  200  can include a housing  209  with an opening  208 . A display  204  surrounded by a frame can be positioned within the opening  208 . Display circuitry for the display  204  can be located within the housing  209 , such as directly below the display  204 . The positioning of the display circuitry can affect the internal spaces that are available within the housing  209 . 
     A touch screen can be associated with the display  204 . Circuitry associated with the touch screen, such as touch screen controller, can be located within the housing  209 . The display  204  can be sealed via a cover glass (or other material)  206 . One or more input buttons, such as input button  214 , can be positioned in an opening of the cover glass  206 . Detection circuitry associated with the input button  214  can be located within the housing  209 . In some examples, the input button  214  can be used to return the device  200  to a particular state, such as a home state. 
     A number of input/output mechanisms can be located around the edges of the housing. For instance, a data/power connector  218  and audio jack  216  can be located on a bottom edge of the housing  209  and a power switch  210  can be located on a top edge of the housing  209 . Housing  209  can also include openings for speakers and/or microphones. Circuitry supporting these components can be packaged internally within the housing  209 . The circuitry can be embodied on various circuit boards or on a single circuit board, such as in System-in-Package assemblies, disposed within the housing. 
     A block diagram of device  200  is shown in  FIG. 2B . The components described above can be controlled by a processor on a MLB  255 . Various internal connections can be provided that allow data to move between the MLB  255  and the various components. The routing of internal data connections can depend on how various components are packaged, including where the MLB  255  can be positioned within the housing  209  and available internal pathways that result after the positioning of the various internal device components. 
     In regards to data connections, MLB  255  can be connected to a display controller  260 , which can be coupled to display  204  (shown in  FIG. 2A ). Further, the MLB  255  can be coupled to audio components, such as a speaker, the audio jack  216  (shown in  FIG. 2A ), a microphone or associated audio circuitry  264  including an audio codec. Further, the MLB  255  can be coupled to the various input devices, such as touch screen  222  coupled to a touch screen controller  262 , the input button circuitry, and the power switch circuitry. In addition, the MLB  255  can be connected to various data interfaces that allow it to receive and send external data, such as the wireless controller  256 , which can include an antenna  266 , and the data/power connector  218 . 
     Besides data connections, many internal device components can receive power from an internal power source, such as battery  230 . For instance, the battery  230  can be coupled to the MLB  255 , the display  204 , the display controller  260 , the touch screen  222 , and the data/power connector  218 . Like the data connections, the routing of the power connections can depend on the positioning of the various internal device components, such as the battery  230  and the available internal pathways within the housing  209 . 
     An exemplary block diagram of device  200  is shown in  FIG. 2C . Various circuitry included in device  200  as described above can be packaged into a single package or a SiP assembly. Several tens or hundreds of electronic components including multiple dies, passive components, and mechanical or optical components can be packaged in a single system on a PCB. Antenna  266 , audio jack  216 , volume switch  212 , data/power connector  218 , wireless controller  256 , audio circuitry  264 , input button  214 , display controller  260 , touch screen controller  262 , and power switch  210  can be included on the MLB  255 . Packaging of the components into a SiP assembly can lead to a thinner, more compact, and sleeker device  200 . 
       FIG. 3  illustrates a perspective view of an exemplary compact portable electronic device that includes components. Portable electronic device  300  can include housing  313 . Housing  313  can be formed from metal, plastic, fiber-composite materials such as carbon fiber materials, glass, ceramics, other materials, or combinations of these materials. Housing  313  can be formed from a single piece of machined metal (e.g., using a unibody-type construction) or can be formed from multiple structures that are attached together such as an internal housing frame, a bezel or band structure, housing sidewalls, planar housing wall members, etc. Device  300  can include components  301 - 307  mounted on a PCB  314  within housing  313 . Components  301 - 307  can include integrated circuits such as general purpose processing units, application-specific integrated circuits, radio-frequency components such as wireless transceivers, clock generation and distribution circuits, or other components such as discrete components. PCB  314  can be a MLB or other types of logic boards. 
     Some of the components  301 - 307  can be sensitive to electromagnetic interference (EMI). For example, a wireless transceiver component can be sensitive to radio-frequency harmonics from a system clock generation component. Some of the components  301 - 307  can produce radio-frequency signal interference (e.g., a cellular transceiver can emit radio-frequency signals that affect other components of device  300 ). Other components can generate magnetic interference (e.g., inductors in a power management system can generate magnetic fields). To ensure that the components of device  300  operate properly, it can be desirable to electromagnetically shield one or more components  301 - 307  on PCB  314  from each other (e.g., by covering components  301 - 307  with shielding structures). 
     Components can be grouped into different subsystems based on their functionality. For example, components  301 - 302  can be included in subsystem  320 , components  303 - 304  can be included in subsystem  322 , and components  305 - 307  can be included in subsystem  324 . As an example, subsystem  320  can be designated for wireless communications and subsystem  322  can be designated for audio. It can be desirable to shield a wireless communications integrated circuit located in subsystem  320  to help insure that system noise (e.g., from clocks or other noise sources) does not interfere with proper receiver operation. It can also be desirable to shield an audio circuit located in subsystem  322  so that the audio circuit does not pick up noise from another circuit on device  300  or to shield memory circuits and processor components so that their clocks do not cause interference with other components. In some examples, it can be desirable to shield a group containing multiple components (e.g., when the components are sensitive to EMI from external sources). 
       FIG. 4  illustrates an exemplary portable electronic device with metal shielding cans used for shielding. Portable electronic device  400  can include a PCB  414  enclosed within housing  410 . Components  401 - 407  can be mounted or disposed on the PCB  414 . Components  401 - 402  can be included in subsystem  420 , components  402 - 403  can be included in subsystem  422 , and components  404 - 407  can be included in subsystem  424 . Shielding cans  430  can be used to cover components within a particular subsystem from either internal interference, external interference, or both. Shielding cans  430  can be soldered onto the PCB  414  either during or after mounting the components to the PCB  414 . In some examples, the shielding cans can be made of a metal sheet or a foil. 
     One possible problem with the shielding cans can be that the shielding cans can occupy a significant portion of board space. Additionally, the sheet thickness of the material used for the shielding cans and additional clearance gap required above the shielding cans can lead to thicker, more bulky devices. 
       FIG. 5  illustrates a cross-sectional view of an exemplary portable electronic device with conductive paste used for shielding. Portable electronic device  500  can include a substrate or PCB  514 . Components  501 ,  503 , and  505  can be mounted or disposed on the PCB  514  using any mounting technique. Shielding structures can include an insulator or insulating layer  516  and a shielding or shielding layer  518 . Shielding structures can be disposed on components  501 ,  503 , and  505  and can selectively shield components  501 ,  503 , and  505  from internal and/or external interference. Insulating layer  516  can be used to prevent electrical shorting between the shielding layer  518  and any conductive materials on PCB  514  (e.g., conductive portions of components  501 ,  503 , and  505 ). 
     Insulating layer  516  can be formed from epoxy, over-molding materials, under-fill materials, heat shrink jackets, acrylic materials, dielectric materials, thermoset materials, thermoplastics, rubbers, plastics, or other desirable materials that provide electrical insulation. In some examples, insulating layer  516  can be formed using insulating materials that are electrically insulating and thermally conductive. For example, insulating material can include thermally conductive plastics, epoxy, or other thermally conductive materials. Insulating materials that are thermally conductive can be used to draw heat away from components  501 ,  503 , and  505 . For example, a radio-frequency transceiver can become undesirably hot during normal operation. In this scenario, it can be desirable to form shielding structures from insulating materials that are thermally conductive to help protect the radio-frequency transceiver from overheating. In some examples, insulating layer  516  can be used to form configurations that can include subsystems for selected components on a substrate. In some examples, insulating layer  516  can be used to form configurations that provide structural support for shielding layer  518 . 
     Shielding layer  518  can be formed over the insulating layer  516  to shield the underlying components from EMI. Shielding layer  518  can include conductive materials such as silver paint, platinum paint, solder, metals such as copper or aluminum, metal alloys such as nickel-iron alloys, conductive adhesives, or other materials suitable for electromagnetic shielding. Shielding layer  518  can be formed in various configurations including walls, fences, sheets or layers, combinations of these configurations, or other desired configurations. 
     PCB  514  can include metal traces  542  and ground plane  546 . Shielding layer  518  can electrically couple with metal traces  542  and ground plane  546  to form a shielding structure that encloses each subsystem and can help protect components  501 ,  503 , and  505  from EMI (e.g., interference from external sources or between components of different subsystems). In some examples, metal traces  542  can be formed from conductive materials that help protect the PCB  514  from cutting tools. For example, metal traces  542  can reflect lasers emitted by laser cutting tools. 
     One possible problem with conductive paste can be its shielding effectiveness. The conductive paste can be porous and can have limited shielding capabilities due to low conductivity. Additionally, the viscosity of the conductive paste can require the width between subsystems to be wide in order for the conductive paste to fill the channels or the area between subsystems. For example, the width W (see  FIG. 5 ) of the channels can be about 100 μm-1 mm. Furthermore, the conductive paste can require additional processing steps such as curing and baking that can lead to long manufacturing times. 
     In some examples, a narrow trench can be formed, and a plating film or a thin-film metal can be deposited to fill the trench. The plating film or thin-film metal can be deposited using any number of techniques, such as chemical vapor deposition, physical vapor deposition, plating, printing, or spray processes. The plating film or thin-film metal can be susceptible to peeling or limited shielding effectiveness due to poor adhesion to underlying layers. The plating film or thin-film metal can also be aesthetically unappealing and/or can be susceptible to environment-induced degradation or discoloration. 
       FIGS. 6A-6D  illustrate cross-sectional views of an exemplary portable electronic device packaged into a System-in-Package assembly with a multi-layer thin-film stack used as shielding.  FIG. 6E  illustrates a flow diagram of an exemplary process for forming the portable electronic devices depicted in  FIGS. 6A-6D . Portable electronic device  600  can include a substrate or PCB  614 , provided in step  660  of process  650 . In step  662 , components  601 - 604  can be mounted or disposed on PCB  614  using any mounting technique. The components  601 - 604  can be mounted using solder or any suitable mounting material. 
     In step  664 , insulating layer  616  can be formed on the PCB  614  using an injection process or a deposition process. For the injection process, molding tools can be used to mold insulating materials to form the insulating layer  616  and to transfer the molded insulating layer  616  to the PCB  614 . Molding tools can include injection molding tools, sintering tools, matrix molding tools, compression molding tools, transfer molding tools, extrusion molding tools, and other tools suitable for molding insulating materials into a desired configuration. Molding tools can be used to form structures that define the shape and location of the subsystems  620  and  622 . For the deposition process, deposition tools can be used to deposit insulating layer  616  at desired locations on the substrate or PCB  614 . Deposition tools can include tools for injecting insulating materials (e.g., epoxy) into injection molding tools to form shielding structures. Deposition tools can also include thin-film deposition tools (e.g., chemical or physical vapor deposition tools) or other tools desirable for forming shielding structures. 
     Insulating layer  616  can be an epoxy, over-molding materials, under-fill materials, heat shrink jackets, acrylic materials, dielectric materials, thermoset materials, thermoplastics, rubbers, plastics, or other desirable materials that provide electrical insulation. In some examples, the insulating layer  616  can be formed by injecting the material into a space inside a molding structure. 
     In step  666 , subsystems  620  and  622  can be formed and defined. Each subsystem  620  and  622  can enclose its respective components  601 - 602  and  603 - 604 , and can be formed either during the molding process as described above or by scribing or etching a channel using a cutting source. When using a molding process, molding structures (not shown) can have holes through which insulating material can be injected into the space inside the molding structure. After the injection process (e.g., after insulating materials are injected and sufficiently cooled), the molding structures can be removed. The insulating materials can be heated prior and/or during injection using heating tools. Heating tools can include oil-based heating tools, gas-based heating tools, electrical-based heating tools, or any other heating tools suitable for heating insulating materials. Heating tools can, if desired, be used to apply pressure to the insulating layer  616  during formation. In some examples, the insulating layer  616  can be pre-formed and then placed on the PCB  614  over the components  601 - 604 . When using a cutting source to define each subsystem  620  and  622 , channels or trenches  630  can be formed by cutting through the insulating layer  616  using cutting tools to isolate subsystems  620  from  622 . In some examples, the width of the trenches  630  can be between 10-100 nm. Cutting tools can include sawing tools, laser cutting tools, grinding tools, drilling tools, electrical discharge machining tools, or other machining or cutting tools suitable for cutting through the insulating layer  616 . 
     In step  668 , an adhesion layer  640  can be deposited on the insulating layer  616  and in the trenches  630 . The adhesion layer  640  can be made of any material that has good adhesion to at least the insulating layer  616  or the subsequently formed shielding layer  642  or both. One example material for the adhesion layer  640  can be Stainless Steel. In some examples, the thickness of the adhesion layer  640  can be between 10-100 nm. 
     In step  670 , a shielding layer  642  can be deposited on the adhesion layer  640  and in the trenches  630 . The shielding layer  642  can be made of any material that has good shielding efficiency or low skin depth, high conductivity, and low cost. The skin depth is the depth at which radiation can penetrate the shielding layer  642 . Materials that can be used for the shielding layer  642  can include, but are not limited to, Copper, Nickel and Silver. In some examples, the thickness of the shielding layer  642  can be between 1-100 μm. In some examples, the thickness of the shielding layer  642  can be greater than 100 μm and can be increased in order to achieve a lower skin depth. 
     In step  672 , a protector or protection layer  644  can be deposited on the shielding layer  642  and in the trenches  630 . The protection layer  644  can be made of any material that has good adhesion to the shielding layer  642  and good corrosion resistance properties. Materials that can be used for the protection layer  644  can include, but are not limited to, Stainless Steel, Gold, and Platinum. 
     In step  674 , a cosmetic layer  646  can be deposited on the protection layer  644  and in the trenches  630 . The cosmetic layer  646  can be made of any material that has the desired cosmetic properties such as color. For example, to achieve a gold color, Titanium Nitride (TiN), Gold (Au), or Zirconium Nitride (ZrN) can be deposited. To achieve a black color, Diamond-like Carbon (DLC), Boron Carbide (B 4 C), Molybdenum Disulfide (MoS 2 ), Aluminum Titanium Nitride (AlTiN), or AlTiN/(Mo,W)S 2  can be deposited. To achieve a dark gray color, Silicon Carbide (SiC), AlTiN/(Mo,W)S 2 , or Chromium Nitride (CrN) can be deposited. To achieve a silver color, Titanium Carbide (TiC), TiC/(Mo,W)S 2  or Silver (Ag) can be deposited. To achieve a bronze color, Titanium Nitride (TiN) or Titanium Carbon Nitride (TiCN) can be deposited. The thickness and composition of the material used for the cosmetic layer  646  can depend on the desired color. In some examples, the thickness of the cosmetic layer  646  can be 100-1000 nm. 
     In some examples, the cosmetic layer  646  can be selectively deposited on top of the protection layer  644  without filling the trench  630 , as shown in  FIG. 6B . In some examples, both the cosmetic layer  626  and protection layer  644  can be selectively deposited on top of the shielding layer  642  without filling the trench  630 , as shown in  FIG. 6C . In some examples, one or more of the adhesion layer  640 , shielding layer  642 , protection layer  644 , and cosmetic layer  646  can be deposited to conformally coat the sides of the assembly, as shown in  FIG. 6D . In some examples, additional adhesion layers can be deposited between any of the layers in the multi-thin film stack. In some examples, the protection layer  644  can be deposited on the cosmetic layer  646 . In some examples, the cosmetic layer  646  can be deposited between the shielding layer  642  and protection layer  644  or between the adhesion layer  640  and the shielding layer  642 . 
     The adhesion layer  640 , shielding layer  642 , protection layer  644 , and cosmetic layer  646  can be deposited using any number of deposition tools including chemical vapor deposition, physical vapor deposition, plating, printing, or spraying. In some examples, the layers of the multi-thin film stack can be deposited in the same system. In some examples, width of the trench  630  can be formed based on the thickness of the layers that fill the trench. 
       FIG. 7A  illustrates a cross-sectional view of an exemplary portable electronic device packaged into a System-in-Package assembly with a multi-layer thin-film stack used as shielding.  FIG. 7B  illustrates a flow diagram of an exemplary process for forming the portable electronic device depicted in  FIG. 7A . To reduce the width of trenches, thereby reducing the board size, one or more layers can be combined into multi-functional layers. For example, the cosmetic layer and protection layer can be combined. 
     Portable electronic device  700  can include a substrate or PCB  714 . The PCB  714  can be provided in step  760  of process  750 . In step  762 , components  701 - 704  can be mounted or disposed on PCB  714  using any mounting technique and using any suitable mounting material such as solder. 
     In step  764 , insulating layer  716  can be formed on PCB  714  using an injection process or deposition process as discussed earlier. Materials used for the insulting layer  716  can include an epoxy, over-molding materials, under-fill materials, heat shrink jackets, acrylic materials, dielectric materials, thermoset materials, thermoplastics, rubbers, plastics, or other desirable materials that provide electrical insulation. In step  766 , subsystems  720  and  722  can be defined during the molding process or by cutting through the insulating layer  716  using any one of the cutting tools as described earlier. 
     In steps  768  and  770 , adhesion layer  740  and shielding layer  742  can be deposited using any deposition technique such as chemical vapor deposition, physical vapor deposition, printing, or spray processes. In step  772 , a multi-functional layer  748  can be deposited on the shielding layer  742  and in the trenches  730  using any one of the deposition techniques. In some examples, the multi-functional layer  748  can be a cosmetic and protection layer. The multi-functional layer or the cosmetic and protection layer  748  can be made of any material that has the desired aesthetic appeal and good corrosion resistance properties. Materials used for the cosmetic and protection layer  748  can include, but are not limited to, SiC, DLC, MoS 2 , AlTiN, B 4 C, AlTiN/(Mo,W)S 2 , TiN, TiC, CrN, and ZrN. In some examples, the cosmetic and protection layer  748  can be made of an inert metal such as Gold or Platinum. The inert metal can help protect the shielding layer  742  and can have good resistance to environmental-induced degradation or discoloration. In some examples, multiple adhesion layers and/or multiple cosmetic and protection layers can be employed. In some examples, the multi-layer thin film stack can be deposited in a single integrated system to minimize or avoid defects, particles, or oxidation issues. In some examples, the thickness of the cosmetic and protection layer  748  can be between 100-1000 nm. 
     In some examples, an electronic device is disclosed. The electronic device may comprise: a substrate; and a system in package assembly including: a plurality of components mounted on the substrate, one or more subsystems, each subsystem including one or more of the plurality of components, and a multi-layer thin film stack disposed between the one or more subsystems, the multi-layer thin film stack up configured to shield the one or more subsystems from interference. Additionally or alternatively to one or more examples disclosed above, in other examples, the electronic device further comprises: an insulator disposed between the plurality of components and a shielding; and a plurality of trenches formed in the insulator, wherein a width of the plurality of trenches is between 10-100 microns. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises an adhesion layer, a shielding, a protector, and a cosmetic layer. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises an adhesion layer, the adhesion layer is made of stainless steel. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises an adhesion layer, a thickness of the adhesion layer is between 10-100 nm. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a shielding. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a shielding, the shielding is at least one of copper, nickel, and silver. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a shielding, a thickness of the shielding is between 1-100 microns. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a protector and the protector is stainless steel. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a cosmetic layer, the cosmetic layer is at least one of Titanium Nitride (TiN), Gold (Au), Zirconium Nitride (ZrN), Diamond-like Carbon (DLC), Boron Carbide (B 4 C), Molybdenum Disulfide (MoS 2 ), Aluminum Titanium Nitride (AlTiN), AlTiN/(Mo,W)S 2 , Silicon Carbide (SiC), Chromium Nitride (CrN), Titanium Carbide (TiC), TiC/(Mo,W)S 2 , Silver (Ag), Titanium Nitride (TiN) and Titanium Carbon Nitride (TiCN). Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a cosmetic layer, a thickness of the cosmetic layer is between 100-1000 nanometers. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises an adhesion layer, a shielding, and a multi-functional layer. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a multi-functional layer, the multi-functional layer is at least one of Silicon Carbide (SiC), Diamond like Carbon (DLC), Molybdenum Sulfide (MoS 2 ), Aluminum Titanium Nitride (AlTiN), Boron Carbide (B 4 C), AlTiN/(Mo,W)S 2 , Titanium Nitride (TiN), Titanium Carbide (TiC), Chromium Nitride (CrN), and Zirconium Nitride (ZrN). Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a multi-functional layer, the multi-functional layer is an inert metal. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises a multi-functional layer, a thickness of the multi-functional layer is between 100-1000 nm. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-layer thin film stack comprises at least one of a protector, cosmetic layer, and a multi-functional layer, the device further comprising: an insulator disposed between the plurality of components and a shielding; and a plurality of trenches formed in the insulator, wherein at least one of the protector, the cosmetic layer, and the multi-functional layer substantially fills the plurality of trenches. Additionally or alternatively to one or more examples disclosed above, in other examples, the multi-functional layer is a cosmetic and protection layer. 
     In some examples, a method for forming an electronic device is disclosed. The method may comprise: forming a substrate; forming a system in package assembly including: mounting a plurality of components on the substrate; forming a multi-layer thin film stack disposed between one or more subsystems, the plurality of components included in the one or more subsystems, wherein the multi-layer thin film stack is configured to shield the one or more subsystems from interference. Additionally or alternatively to one or more examples disclosed above, in other examples, forming the multi-layer thin film stack comprises: depositing an adhesion layer; depositing a shielding; depositing a protector; and depositing a cosmetic layer. Additionally or alternatively to one or more examples disclosed above, in other examples, forming the multi-layer thin film stack comprises: depositing an adhesion layer; depositing a shielding; and depositing a multi-functional layer. 
     While various examples have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Although examples have been fully described with reference to the accompanying drawings, the various diagrams can depict an example architecture or other configuration for this disclosure, which is done to aid in the understanding of the features and functionality that can be included in the disclosure. The disclosure is not restricted to the illustrated exemplary architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, although the disclosure is described above in terms of various examples and implementations, it should be understood that the various features and functionality described in one or more of the examples are not limited in their applicability to the particular example with which they are described. They instead can be applied alone or in some combination, to one or more of the other examples of the disclosure, whether or not such examples are described, whether or not such features are presented as being part of a described example. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described examples.

Metadata:
Filing Date: 20191219
Publication Date: 20220301
Grant Date: 20220301
Priority Date: 20140318
Inventors: CHEN, YANFENG
PENNATHUR, SHANKAR S.
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K3/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L2924/3025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10371", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K3/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K2201/09972", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K9/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T29/49146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2924/3025", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/0715", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09972", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/10371", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/10371", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K9/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01L2924/3025", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T29/49146", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/09972", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K9/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0218", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2203/1322", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 54143493