PATENT DOCUMENT

Publication Number: US-9585275-B2
Application Number: US-201414473065-A
Country: US
Kind Code: B2

Title: Electronic devices with moisture guiding structures

Abstract:
Electronic devices may have housings in which components are mounted. Some of the components may be sensitive to moisture. Other components may be insensitive to moisture and may form openings in a device housing that allow moisture to escape from within the housing. Components may be mounted on substrates such as printed circuit board substrates. Moisture repelling layers and moisture attracting layers may be patterned to form channels and other structures that guide moisture away from sensitive components towards insensitive components. Moisture repelling and attracting layers may also be used to limit the lateral spread of a conformal coating layer when coating components.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 at least one electronic component mounted on a substrate in the housing; 
 a coating on the substrate that surrounds the at least one electronic component; 
 a conformal coating that covers the at least one electronic component and is laterally constrained by the coating that surrounds the at least one electronic component, wherein the conformal coating is in direct contact with the coating and wherein the conformal coating and the coating are non-overlapping; and 
 a hydrophobic coating that is formed in direct contact with the conformal coating, wherein the hydrophobic coating overlaps substantially all of the conformal coating. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the coating on the substrate that surrounds the at least one electronic component comprises an additional hydrophobic coating. 
     
     
       3. The electronic device defined in  claim 2  wherein the at least one electronic component covered by the conformal coating is a moisture-sensitive electronic component. 
     
     
       4. The electronic device defined in  claim 3  further comprising:
 a connector mounted in the housing; and 
 a patterned hydrophilic coating layer on the substrate, wherein the patterned hydrophilic coating layer forms a moisture guiding channel that directs moisture away from the moisture-sensitive electronic component towards the connector. 
 
     
     
       5. The electronic device defined in  claim 1  wherein the coating on the substrate that surrounds the at least one electronic component comprises an oleophobic coating. 
     
     
       6. The electronic device defined in  claim 5  wherein the at least one electronic component covered by the conformal coating is a moisture-sensitive electronic component. 
     
     
       7. The electronic device defined in  claim 6  further comprising:
 a connector mounted in the housing; and 
 a patterned hydrophilic coating layer on the substrate, wherein the hydrophilic coating layer forms a moisture-guiding channel that directs moisture away from the moisture-sensitive electronic component towards the connector. 
 
     
     
       8. The electronic device defined in  claim 1 , wherein the hydrophobic coating is formed from a material selected from the group consisting of: parylene, silicone, and polytetrafluoroethylene. 
     
     
       9. The electronic device defined in  claim 8 , wherein the coating on the substrate is formed from a material selected from the group consisting of: parylene, silicone, and polytetrafluoroethylene. 
     
     
       10. The electronic device defined in  claim 9 , wherein the conformal coating is formed from a material selected from the group consisting of: epoxy, silicone, parylene, acrylic, and polyurethane. 
     
     
       11. An electronic device, comprising:
 a housing; 
 a printed circuit board in the housing; 
 at least one moisture-sensitive electronic component mounted to the printed circuit board; 
 a coating on the printed circuit board that surrounds the at least one moisture-sensitive electronic component; 
 a conformal coating that covers the at least one moisture-sensitive electronic component and is laterally constrained by the coating that surrounds the at least one moisture-sensitive electronic component; and 
 patterned coating layers on the printed circuit board that direct water away from the at least one moisture-sensitive electronic component and towards a moisture-insensitive component in the electronic device, wherein the patterned coating layers include a patterned hydrophilic coating layer on the substrate, and wherein the patterned hydrophilic coating layer forms a moisture guiding channel that directs moisture away from the at least one moisture-sensitive electronic component. 
 
     
     
       12. The electronic device defined in  claim 11  wherein the patterned coating layers comprise first and second portions of a hydrophobic coating layer, and wherein the hydrophilic coating layer is bordered by and interposed between the first and second portions of the hydrophobic coating layer. 
     
     
       13. The electronic device defined in  claim 12  wherein the hydrophilic coating layer comprises a material selected from the group consisting of: metal oxide, material in which metal oxide particles have been incorporated within a binder, polyurethane, and polyethylene oxide, and wherein the hydrophobic coating layer comprises a material selected from the group consisting of: parylene, silicone, and polytetrafluoroethylene. 
     
     
       14. An electronic device, comprising:
 a housing; 
 at least one electronic component mounted on a substrate in the housing; 
 a moisture-insensitive component mounted in the housing; and 
 a patterned hydrophilic coating layer on the substrate, wherein the patterned hydrophilic coating layer forms a moisture guiding channel that directs moisture away from the at least one electronic component towards the moisture-insensitive component.

Description:
This application is a division of patent application Ser. No. 12/871,804, filed Aug. 30, 2010, which is hereby incorporated by reference herein in its entirety. This application claims the benefit of and claims priority to patent application Ser. No. 12/871,804, filed Aug. 30, 2010. 
    
    
     BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to materials within electronic devices that control moisture. 
     Electronic devices are often exposed to moist environments. As an example, a user may operate a cellular telephone or media player outdoors when there is precipitation. Devices may also be exposed to moisture in the form of perspiration. 
     Waterproof devices are able to withstand exposure to moisture. Waterproof housings are, however, often impractical for normal use. Conventional electronic devices are therefore vulnerable to moisture-induced damage, particularly when sensitive device components such as buttons are subjected to prolonged contact with moisture. 
     Conformal coatings are sometimes used to encapsulate device components and make them less vulnerable to moisture exposure. It can be difficult, however, to accurately control the application of conformal coatings, because conformal coatings often have a tendency to spread out over the substrates on which they are applied. Conformal coatings are also not always effective at blocking moisture. 
     It would therefore be desirable to be able to provide electronic devices with improved configurations for protecting vulnerable device components from exposure to moisture. 
     SUMMARY 
     Electronic devices may have housings in which components are mounted. An electronic device may, for example, have buttons, input-output port connectors, integrated circuits, displays, microphones, speakers, sensors, and other components. 
     Some of the components may be sensitive to moisture. For example, components such as buttons based on dome switches may be sensitive to the presence of water. 
     Other components may be insensitive to moisture and may form openings in a device housing that allow moisture to escape from within the housing. For example, a data port connector may have input-output pins that are relatively unaffected by small amounts of moisture and that may be mounted in an opening at the lower end of a device where moisture can exit the device. 
     During normal operation, a device may be exposed to moisture from precipitation or perspiration. The moisture may enter the interior of the housing of an electronic device through gaps. To prevent damage to sensitive components mounted within the device housing, moisture repelling and attracting layers may be patterned on printed circuit boards, conformal coating layers, and other internal structures of the device. 
     For example, moisture repelling layers and moisture attracting layers may be patterned on printed circuit board substrates with or without conformal coating layers to form channels that guide moisture away from sensitive components towards insensitive components. Moisture repelling and attracting layers may also be used to limit the lateral spread of a conformal coating layer during the process of forming the conformal coating layer over a sensitive component. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment of the present invention. 
         FIG. 2  is a cross-sectional side view of a portion of an electronic device including a button and internal device components such as a button switch and mounting structures in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of a conventional encapsulated integrated circuit showing how moisture can penetrate encapsulant pinholes. 
         FIG. 4  is a cross-sectional side view of a component such as an integrated circuit that is covered with encapsulant showing how patterned coatings may be used to prevent moisture damage in accordance with an embodiment of the present invention. 
         FIG. 5  is a top view of an interior of an illustrative electronic device showing how coatings can be patterned to create a moisture flow path between a sensitive component region and an insensitive component region in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram showing how coating patterning equipment may be used to provide coatings with the ability to repel and attract liquids in accordance with an embodiment of the present invention. 
         FIG. 7  is a cross-sectional side view of device structures that have been coated with patterned layers such as a liquid repelling coating layer in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of device structures that have been coated with patterned layers such as a liquid attracting coating layer in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional side view of device structures that have been coated with patterned layers such as liquid attracting and liquid repelling coating layers in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of device structures with patterned liquid attracting and liquid repelling coating layers and a patterned interface layer in accordance with an embodiment of the present invention. 
         FIG. 11  is a top view of device structures including sensitive device components showing an illustrative pattern of liquid attracting and repelling layers that may be used to prevent liquid from coming into prolonged contact with sensitive device components in accordance with an embodiment of the present invention. 
         FIG. 12  is a top view of device structures including sensitive device components showing an illustrative pattern of liquid attracting and repelling layers that may be used to create a multibranch channel for guiding liquid between a moisture entrance location and a moisture exit location that is away from the sensitive device components in accordance with an embodiment of the present invention. 
         FIG. 13  is cross-sectional side view of a conventional conformal coating that is covering an integrated circuit on a printed circuit board. 
         FIG. 14  is a cross-sectional side view of a device component mounted on a substrate that has a patterned liquid repelling coating layer such as an oleophobic layer in accordance with an embodiment of the present invention. 
         FIG. 15  is a cross-sectional side view of the device component of  FIG. 14  showing how a conformal coating may be laterally constrained by the patterned liquid repelling coating layer in accordance with an embodiment of the present invention. 
         FIG. 16  is a flow chart of illustrative steps involved in forming device structures that incorporate patterned liquid repelling regions and liquid attracting regions in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic device  10  of  FIG. 1  may be a cellular telephone, media player, computer, handheld device, portable computer, tablet computer, Global Positioning System device, camera, gaming device, or other electronic equipment. 
     As shown in  FIG. 1 , device  10  may have a housing such as housing  12 . Housing  12  may be formed from plastic, metal, carbon fiber composite material, other composites, glass, ceramics, other materials, or combinations of these materials. Housing  12  may be formed from multiple pieces of material or may be formed using a unibody construction in which housing  12  is substantially formed from a single structure (e.g., machined or cast metal, plastic, etc.). 
     Device  10  may have input-output devices such as input-output ports, speakers, microphones, displays, status indicator lights, touch screens, buttons, proximity sensors, wireless circuitry, accelerometers, ambient light sensors, touch pads, and other devices for accepting input from a user or the surrounding environment of device  10  and/or for providing output to a user of device  10 . 
     As shown in the illustrative configuration of  FIG. 1 , device  10  may, as an example, have a display such as touch screen display  14 . One or more buttons  16  may be used to gather user input. Buttons  16  may be based on dome switches or other switch circuitry. Buttons  16  may include button members that form push buttons (e.g., momentary buttons), slider switches, rocker switches, etc. Connector port  18  may be, for example, a 30-pin connector for a 30-pin data port, a Universal Serial Bus port, or other input-output port. Port  19  may be, for example, a signal port such as an audio jack for receiving an audio plug. Additional buttons such as buttons  16 , additional data ports such as port  18 , and additional signal ports such as audio connector port  19 , and other input-output devices may be provided if desired. The example of  FIG. 1  is merely illustrative. 
     Devices such as device  10  may be vulnerable to moisture. For example, moisture may wick into gaps in device housing  12  or gaps between internal device components. When moisture reaches sensitive device components such as button components, integrated circuits, or other circuitry that is susceptible to malfunctions when wet, device  10  may fail. 
       FIG. 2  is a cross-sectional view of a portion of device  10  in the vicinity of one of buttons  16 . As shown in  FIG. 2 , button  16  may have a button member such as button member  22  that reciprocates within opening  20  of housing  12 . When a user presses the exterior of button member  22  in direction  24 , portion  28  of button member  22  may press against a dome switch or other switch mechanism in switch structure  30 , thereby activating the switch (e.g., shorting internal switch terminals together to close the switch). A dome member or other biasing element may push button member  22  outward in direction  26  when the user releases pressure from button member  22 . 
     A support bracket such as support bracket  32  may be used to mount switch structure  30 . To prevent moisture that has intruded into the interior of device  10  from contacting switch structure  30 , switch structure  30  may be sealed from the interior (INT) of device  10  using flexible sheet  36 . Sheet  36  may be formed from a moisture barrier material such as a layer of polyimide (e.g., a polyimide flexible printed circuit of the type that is sometimes referred to as a flex circuit). Flex circuit  36  may be attached to bracket  32  using adhesive  38 . Adhesive  38  may help form a seal between flex circuit  36  and nearby structures such as the interior walls of device housing  12  and internal housing member  34 . Nevertheless, gaps may form such as illustrative gap  38 , that allow moisture to penetrate region  40  adjacent to switch structure  30  from interior INT. Moisture may also penetrate region  40  through the gaps that are formed between the surface of button member  22  and the surrounding sidewalls of opening  20  of housing  12 . 
     Switch structure  30  may include a dome switch or other mechanism that is prone to failure if exposed to moisture (e.g., short term and/or long term moisture exposure from water or other liquids). Switch structure  30  therefore represents an example of a device component that exhibits sensitivity to moisture. Other moisture-sensitive device components may include integrated circuits, discrete circuit components such as resistors, inductors, and capacitors, display structures, touch sensor circuitry, and sensor circuits (as an example). These sensitive circuits may be vulnerable to moisture exposure due to weather conditions, perspiration, accidental spills, and other sources. 
     Other components in device  10  may be relatively insensitive to moisture. An example of a component that may be considered insensitive to moisture is connector  18 . Connector  18  may contain input-output pins that receive a mating connector (e.g., a 30-pin plug on the end of a cable). Although connector  18  may not be waterproof, it may be less likely to exhibit a serious failure than sensitive component such as one of buttons  16  when exposed to moisture. 
     In environments such as these, it may be advantageous to control the flow of moisture within device  10 . Coatings such as coatings that repel and attract moisture may be patterned to form regions of device  10  that repel moisture (e.g., regions that repel moisture away from sensitive components) and regions that attract moisture (e.g., moisture guiding channels that help route water away from sensitive components and towards insensitive components). A moisture repelling coating may, for example, be used to cover some or all of flex circuit  36  and gap  38  of  FIG. 2  to direct moisture away from gap  38 . Components such as connector  18  may not only be relatively insensitive to moisture, but may also serve as exit ports that allow moisture to escape from the interior of housing  12 . Structures that guide moisture towards components such as connector  18  may therefore help reduce moisture damage. 
       FIG. 3  is a cross-sectional side view of a conventional integrated circuit mounting arrangement. As shown in  FIG. 3 , integrated circuit  46  has been mounted on printed circuit board  44 . Conformal coating  48  has been used to cover integrated circuit  46 . Conformal coating  48  may have a pinhole such a pinhole  50 . When moisture  52  (e.g., water) comes into contact with conformal coating  48 , some of moisture  52  may penetrate through coating  48  via pinhole  50 . If moisture  52  reaches component  46 , component  46  may fail. 
       FIG. 4  is a cross-sectional side view of a component mounting scheme of the type that may be used within device  10  of  FIG. 1 . As shown in  FIG. 4 , component  60  may be mounted on substrate  58 . Component  60  may be an integrated circuit, a button (e.g., a dome switch for a button), or other sensitive device component. Substrate  58  may be a rigid printed circuit board substrate (e.g., fiberglass filled epoxy such as FR4), a flexible polymer printed circuit board such as a polyimide printed circuit board (i.e., a “flex circuit”), rigid flex, glass, ceramic, or other substrate. Device components can also be mounted on housing structures and other structures in device  10 . 
     Conformal coating  68  may be used to cover component  60 . Conformal coating  68  may be formed from materials such as epoxy, silicone, parylene, acrylic, polyurethane, other polymers, other dielectrics, etc. 
     To help prevent moisture  56  from reaching sensitive component  60  and to help control the lateral dimensions of conformal coating  68 , patterned coating layers such as layer  64  may be formed on substrate  58 . Layer  64  may include liquid repelling coating material and/or liquid attracting coating material. As an example, material  64 A may be formed from a material such as an oleophobic coating material that repels conformal coating  68  and thereby constrains the lateral dimensions of coating  68  and layer  64 B may be a hydrophobic material that repels moisture  56  (e.g., so that moisture  56  travels in direction  66 ). By preventing moisture  56  from resting above pinhole  62  in conformal coating  68 , moisture penetration to sensitive component  60  may be avoided or reduced. 
     Coating layers such as layer  64  may repel liquids such as water, liquids such as conformal coating materials, and other liquids (e.g., oils, adhesives, etc.). Coating layers such as layer  64  are sometimes referred to herein as hydrophobic layers (layers that repel liquids such as water and potentially other liquids), hydrophilic layers (layers that attract liquids such as water and potentially other liquids), oleophobic layers (layers that repel oils and oily substances and that may potentially repel other liquids and conformal coatings), and oleophilic layers (layers that attract oils and oily substances and that may potentially attract other liquids and conformal coatings). The properties of these coating materials need not be mutually exclusive. For example, a hydrophobic coating may also be oleophobic, a hydrophilic coating may also be oleophilic, etc. 
     Examples of hydrophobic materials that may be patterned to form patterned hydrophobic coating layers include parylene, silicone, and polytetrafluoroethylene. Materials such as these may also be oleophobic. Examples of hydrophilic materials that may be patterned to form patterned hydrophilic coating layers include metal oxides (e.g., titanium dioxide), materials in which metal oxide particles have been incorporated within a binder, polyurethanes, and polyethylene oxide. Materials such as these may also be oleophilic. Surface treatments may also be used to form moisture attracting and moisture repelling regions. For example, a surface (e.g., a surface of one material or a surface of multiple materials) may be roughened to increase its hydrophilic and oleophilic properties or may be smoothed to decrease these properties. 
     Coating layers such as layer  64  may be applied and patterned by spraying, dipping, inkjet printing, painting, pad printing, screen printing, shadow masking, lift-off, etc. Coating layers may be heated to dry out the coating material and/or to thermally cure the material. Coating layers may also be cured by application of light and using two-part chemical mixtures. 
     Layers such as layer  64  may be patterned to control the positioning and movement of conformal coatings such as coating  68  and/or to control the positioning and movement of moisture that intrudes into the interior of device  10  such as water (e.g., from precipitation, from perspiration, etc.). 
       FIG. 5  is a top view of the interior of an illustrative electronic device. As shown in the example of  FIG. 5 , device  10  may have one or more internal structures such as printed circuit boards, other substrates, and other mounting structures (e.g., parts of housing  12 , etc.) that are mounted within housing  12  (i.e., the structures shown as being located within the rectangular boundary of housing  12  in  FIG. 5 ). Sensitive components  72  (e.g., a sensitive component such as sensitive component  60  of  FIG. 4 ) may be mounted on these internal structures. A sensitive component such as button  16  may be mounted on internal structures such as a printed circuit board or support structure through an opening in a sidewall of housing  12 . 
     Water may enter the interior of device  10  through a gap between button  16  and housing  12 . To prevent sensitive components  72  from becoming damaged and to route the intruding water (or other moisture) away from button  16  and towards a safer location, coating layers may be patterned to form a moisture guiding structures. For example, region  70  and region  78  may be coated with a moisture repelling layer such as a hydrophobic coating. Region  74  may be coated with a moisture attracting substance such as a hydrophilic coating (or a coating that is at least less hydrophobic than the coatings of regions  70  and  78 ). Dashed line  80  represents the boundary between hydrophobic region  70  and hydrophilic (or at least less hydrophobic) region  74 . Dashed line  82  represents the boundary between hydrophobic region  78  and hydrophilic (or at least less hydrophobic) region  74 . 
     Connector  18  may be a 30-pin data connector that mates with corresponding 30-pin data connector  84  when connector  84  is moved in direction  86 . Connector  19  may be an audio jack that receives audio plug  88  when plug  88  is moved in direction  90 . Connectors (e.g., connector  18 ) may be less sensitive than components such as button  16  (e.g., a dome-switch button) when exposed to water and other moisture. Connectors such as connector  18  may also serve as an opening (exit) that allows internal moisture to pass from the interior of device  10  to the exterior of device  10 . In this type of device environment, it may be desirable to direct moisture away from button  16  towards connector  18  (or, in robust audio jack configurations, towards connector  19 ). This prevents the moisture from remaining near button  16 , which is sensitive, and allows the moisture to reside instead near connector  18 . The opening formed by connector  18  may also allow the moisture to escape from device  10 . 
     The pattern formed by regions  70 ,  74 , and  78  may form a moisture-guiding path (e.g., a path bounded by lines  80  and  82  and covering the area occupied by region  74 ). As indicated by arrow  76 , the moisture-guiding path may help guide moisture from button  16  to connector  18 . By encouraging moisture to move from the vicinity of button  16  to the vicinity of connector  18 , potential device failures may be minimized. The use of hydrophobic coatings over regions  70  and  78  may also serve to repel moisture from underlying sensitive components  72 . 
       FIG. 6  shows a system (system  92 ) in which tools  98  may be used to form patterned coating layers for structures in device  10 . Initially, no coatings may be applied, as shown on the left of  FIG. 6 . In this configuration, structures  94  and optional conformal coating  96  may be uncovered by additional coatings. Structures  94  may be substrates such as printed circuit boards (flex circuits, rigid printed circuit boards, or rigid flex), components mounted on printed circuit boards (e.g., integrated circuit packages), sensitive components such as component  60  of  FIG. 4  and components  72  of  FIG. 5 , other components, structures such as internal housing structures, etc. Layer  96  may be a conformal coating such as coating  68  of  FIG. 4  and may include embedded sensitive components such as component  60  of  FIG. 4  and components  72  of  FIG. 5 . 
     As indicated by arrow  100 , materials such as moisture attracting coatings and moisture repelling coatings may be applied by tools  98 . Following application of these materials, the surface of conformal coating  96  (or, if conformal coating  96  is not present, structures such as device components, substrates, etc.) may be covered with patterned layers. The patterned layers may include moisture repelling layers such as layer  64  (e.g., a hydrophobic layer). The patterned layers may also include moisture attracting layers such as layer  104  (e.g., a hydrophilic layer). Other layers such as layer  108  may also be formed. Layers such a layer  108  may be more or less hydrophobic than layer  64  (or may be equally hydrophobic) and may be more or less hydrophilic than layer  104  (or may be equally hydrophilic). Uncoated regions such as uncoated surface  106  may also be formed. The water repelling and water attracting characteristics of surface  106  are determined by the nature of the underlying material (i.e., coating  96  or the surface of structures  94  in configurations in which coating  96  is omitted). 
       FIG. 7  shows an illustrative arrangement in which hydrophobic layer  64  is being used to repel water  56  so that water  56  moves to uncoated region  106  (e.g., in a situation in which uncoated region  106  on layer  96  is more hydrophilic than layer  64  and when layer  64  is therefore more hydrophobic than region  106 ). 
       FIG. 8  shows an illustrative arrangement in which hydrophilic layer  104  is being used to attract water  56  away from region  106  (e.g., in a situation in which layer  104  is more hydrophilic than uncoated surface  106  of layer  96 ). 
       FIG. 9  shows an illustrative arrangement in which both hydrophobic layer  64  and hydrophilic layer  104  have been formed on coating layer  96 . In this situation, water  56  will be attracted away from layer  64  and towards layer  104  because layer  104  is less hydrophobic and more hydrophilic than layer  64 . 
     In the configuration of  FIG. 10 , an interface layer such as layer  114  has been interposed between surface layers such as layer  64  and layer  104 . It may be difficult to adhere surface layers such as moisture repelling layers to underlying layers such as layer  96 . Interface layer  114  may help form an adhesion promotion layer that helps surface layers bond to layer  96 . Layer  114  may be formed from ink, polymer, or other suitable coating materials. 
     Patterns of openings may be formed in the surface layers, interface layer  114 , and coating layer  96  to expose surfaces such as surface  110  of coating  96  (which may be hydrophobic) and surface  112  of structures  94  (which may be hydrophobic). Using arrangements of this type, a substrate such as a polyimide substrate (e.g., a flex circuit) such as layer  94  may have mounted sensitive components that are covered with conformal layer  96  and/or conformal layer  96  may be omitted from all or some of layer  94 . Ink layer  114  may be patterned to form an adhesion promotion layer for an a subsequent matching hydrophobic layer such as layer  64 . Polyimide is naturally hydrophilic, so the uncovered polyimide pattern in this arrangement forms a moisture-guiding channel bounded by hydrophobic region  64 . 
     A top view of internal device structures that have been covered with patterned layers of hydrophobic and/or hydrophilic materials is shown in  FIG. 11 . In the illustrative configuration of  FIG. 11 , moisture enters structures  94  at entrance points IN. Moisture then flows in the direction of arrows  116 . Region  104  may be covered with a hydrophilic material and region  64  may be covered with a hydrophobic material (i.e., region  64  may be more hydrophobic and less hydrophilic than region  104 ). This pattern may therefore cause moisture to be deflected from paths  116  towards exit location OUT along paths  118 . 
       FIG. 12  shows an illustrative configuration in which the coating pattern on structures  94  has been used to form a multibranch moisture guiding channel (hydrophilic region  104 ) that is bounded by hydrophobic regions  64 . The channel may help guide moisture from moisture ingress points IN towards moisture exit location OUT. 
       FIG. 13  is a cross-sectional side view of a conventional conformal coating  48  covering integrated circuit  46  on printed circuit board  44 . As shown in  FIG. 13 , the surface of board  44  may attract conformal coating  48 , causing conformal coating  48  to spread significantly until reaching relatively wide lateral dimension W. 
       FIG. 14  shows how moisture repelling coating material such as material  64 A may be formed around sensitive component  60  (e.g., a sensitive component such as component  60  of  FIG. 4 ). Material  64 A may be provided in a layer that has the shape of a ring with a central rectangular or circular opening (as examples). Material  64 A may be formed from an oleophobic (hydrophobic) substance that repels conformal coating layer  68 . When layer  68  is deposited over component  60 , the presence of material  64 A ensures that layer  68  extends laterally only as far as lateral dimension N, as shown in  FIG. 15 . Lateral dimension N may be smaller than dimension W of  FIG. 13  and/or may be more well controlled than dimension W. 
     Illustrative steps involved in forming moisture repelling and moisture attracting layers in device  10  and/or in forming conformal coating layers in device  10  are shown in  FIG. 16 . 
     At step  120 , a patterned layer such as layer  64 A of  FIG. 14  may be formed on a support structure such as substrate  58  (e.g., structures  94  of  FIG. 6 ). During the operations of step  120 , a conformal coating layer such as layer  68  of  FIG. 15  may be formed over one or more sensitive components  60 . The presence of layer  64 A (e.g., a hydrophobic and/or oleophobic layer) may limit the lateral spreading of conformal coating layer  68  (e.g., to help confine layer  68  to the region surrounding sensitive component  60 ). 
     At step  122 , other device structures may be formed (e.g., by mounting sensitive components such as components  60  and  72  and other internal components for device  10  to printed circuits boards, housing structures, ceramic substrates, glass substrates, underlying devices, and other support structures). These device structures may optionally be coated with conformal coating material (e.g., without using moisture repelling layers such as layer  64 A of  FIG. 15 ). 
     During the operations of step  124 , moisture repelling coatings may be deposited and patterned (e.g., hydrophobic coating layers such as layer  64  may be formed during the operations of step  126 ) and moisture attracting coatings may be deposited and patterned (e.g., hydrophilic coating layers such as layer  104  may be formed during the operations of step  128 ). One, two, three, four, or more than four different regions may be formed, each having a potentially different respective amount of hydrophobic and hydrophilic behavior. Tools  98  may be used in forming patterned coating layers and/or layers such as conformal coating layer  96 . Techniques that may be used by tools  98  in forming layers during step  124  include spraying, dipping, inkjet printing, painting, pad printing, screen printing, shadow masking, lift-off, etc. Light may be applied to cure deposited layers, lasers and other tools may be used to pattern layers, layers may be heated to cure and/or dry materials, etc. 
     Following formation of the layers of step  124  (or earlier, in step  122  or step  120 ), the patterned layers and underlying structures may be mounted in housing  12  of device  10 . 
     A completed device (e.g., device  10  of  FIG. 1 ) may be exposed to moisture during normal operation (step  130 ). When exposed in this way, the moisture repelling regions on structures  94 , the moisture attracting regions on structures  94 , and the associated moisture-guiding channels and other structures that are formed may help to guide and move moisture away from buttons  16  and other sensitive device components and device locations towards connector  18  and other insensitive components and device locations. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140829
Publication Date: 20170228
Grant Date: 20170228
Priority Date: 20100830
Inventors: ALVAREZ FELIX
YATES KYLE H.
Assignee: APPLE INC
CPC Classifications: [{"code": "B05D1/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/065", "inventive": true, "first": true, "tree": "[]"}, {"code": "B05D1/322", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/1427", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/0213", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/284", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/322", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "B05D1/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/0213", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/069", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/1427", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K3/282", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K5/065", "inventive": true, "first": true, "tree": "[]"}, {"code": "H05K5/0212", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 45697030