PATENT DOCUMENT

Publication Number: US-9144938-B2
Application Number: US-201213567949-A
Country: US
Kind Code: B2

Title: Methods for attaching structures using ultraviolet and visible light curing adhesive

Abstract:
An electronic device may be provided with electronic device structures such as housing structures and structures associated with electrical components. The electronic device structures may be attached to each other using ultraviolet and visible light curable adhesive. A layer of adhesive may be interposed between electronic device structures. A light source may generate ultraviolet light. The structures may include an ultraviolet-light-transparent structure through which the ultraviolet light passes to illuminate and cure the adhesive. The ultraviolet-light-transparent structure may form one of multiple shots of injection molded plastic in a device structure, may be formed using a plastic that is opaque at visible wavelengths, or may have a coating such as a metal coating to help reflect ultraviolet radiation onto the adhesive. Perforations in the coating may be used to pass ultraviolet radiation to the adhesive.

Claims:
What is claimed is: 
     
       1. A method, comprising:
 forming a two-shot plastic structure using first and second shots of plastic in injection molding equipment, wherein the first shot of plastic comprises ultraviolet-light-transparent plastic; 
 applying adhesive between the two-shot plastic structure and an additional structure, wherein the adhesive is configured to be cured by exposure to at least ultraviolet light; and 
 applying ultraviolet light to the adhesive through the ultraviolet-light-transparent plastic in the two-shot plastic structure to cure the adhesive. 
 
     
     
       2. The method defined in  claim 1  wherein the second shot of plastic comprises plastic that is opaque to ultraviolet light. 
     
     
       3. The method defined in  claim 2  wherein the additional structure comprises a camera window and wherein applying the ultraviolet light comprises applying the ultraviolet light to the adhesive to attach the camera window to the two-shot plastic structure. 
     
     
       4. The method defined in  claim 1  wherein forming the two-shot plastic structure comprises:
 injection molding the ultraviolet-light-transparent plastic; and 
 injection molding plastic that is opaque at visible light wavelengths over the ultraviolet-light-transparent plastic. 
 
     
     
       5. An apparatus, comprising:
 a plastic structure having first and second plastic portions, wherein the first plastic portion comprises ultraviolet-light-transparent plastic and wherein the second plastic portion comprises plastic that is opaque at visible light wavelengths; 
 a structure associated with an electronic device; and 
 adhesive that attaches the plastic structure to the structure associated with the electronic device, wherein the adhesive has been cured with at least ultraviolet light. 
 
     
     
       6. The apparatus defined in  claim 5  wherein the plastic structure comprises a two-shot injection molded plastic structure. 
     
     
       7. The apparatus defined in  claim 6  wherein the structure associated with the electronic device comprises a clear structure having a layer of opaque masking material. 
     
     
       8. A method for attaching structures for an electronic device, comprising:
 applying adhesive between first and second structures, wherein the first structure comprises plastic that is transparent to ultraviolet light and opaque to visible light and wherein the adhesive is configured to be cured by exposure to ultraviolet light; and 
 curing the adhesive by applying ultraviolet light to the adhesive through the first structure. 
 
     
     
       9. The method defined in  claim 8  wherein the second structure comprises a plastic structure and wherein curing the adhesive comprises attaching the first structure to the plastic structure. 
     
     
       10. The method defined in  claim 8  wherein the plastic of the first structure exhibits more than 70% transmission of ultraviolet light and wherein curing the adhesive comprises transmitting ultraviolet light through the plastic that exhibits more than 70% transmission of ultraviolet light. 
     
     
       11. The method defined in  claim 10  wherein the plastic of the first structure exhibits less than 30% transmission of visible light and wherein curing the adhesive comprises transmitting ultraviolet light through the plastic that exhibits less than 30% transmission of visible light. 
     
     
       12. An apparatus, comprising:
 a first electronic device structure that is transparent to ultraviolet light and opaque to visible light; 
 a second electronic device structure; and 
 a layer of adhesive interposed between the first electronic device structure and the second electronic device structure, wherein the adhesive has been cured by exposure to at least ultraviolet light. 
 
     
     
       13. The apparatus defined in  claim 12  wherein the first electronic device structure comprises plastic. 
     
     
       14. The apparatus defined in  claim 13  wherein the plastic of the first electronic device structure exhibits more than 70% transmission of ultraviolet light. 
     
     
       15. The apparatus defined in  claim 13  wherein the plastic of the first electronic device structure exhibits less than 30% transmission of visible light. 
     
     
       16. The apparatus defined in  claim 13 , wherein the second electronic device structure comprises plastic. 
     
     
       17. The apparatus defined in  claim 16 , wherein the second electronic device structure comprises injection-molded plastic. 
     
     
       18. The apparatus defined in  claim 12  wherein the first electronic device structure comprises injection-molded plastic. 
     
     
       19. The apparatus defined in  claim 12 , further comprising a coating that at least partly covers the first electronic device structure. 
     
     
       20. The apparatus defined in  claim 19 , wherein the coating comprises an opaque coating. 
     
     
       21. The apparatus defined in  claim 20 , wherein the opaque coating comprises a metal layer. 
     
     
       22. The apparatus defined in  claim 20 , wherein the coating includes a plurality of holes configured to pass light to the layer of adhesive.

Description:
BACKGROUND 
     This relates generally to adhesives and, more particularly, to curing adhesives using ultraviolet and visible light. 
     Adhesives are widely used to attach structures to each other. As an example, electronic devices such as computers and cellular telephones often contain adhesives for mounting components to housing structures, for attaching housing structures to each other, and for otherwise assembling structures within a completed device. 
     Thermally cured adhesives can be difficult to control and involve the use of elevated temperatures. The use of elevated temperatures may not be desirable, because many devices include sensitive components with relatively low temperature tolerances. In contrast, ultraviolet and visible (UV/Vis) light curing adhesives can be cured immediately upon application of UV/Vis radiation at room temperature. The ease of controlling the curing process and the relatively low temperatures involved in curing make UV/Vis radiation curing adhesives satisfactory in a wide range of applications. 
     It can be challenging, however, to use UV/Vis radiation curing adhesives in assemblies that contain opaque structures. If care is not taken, the opaque nature of a structure may cause the structure to block UV/Vis radiation from reaching the adhesive during the curing process. If too much UV/Vis radiation is blocked, the adhesive may be poorly cured. 
     It would therefore be desirable to be able to provide improved electronic device structures to facilitate the use of UV/Vis radiation curing adhesives. 
     SUMMARY 
     An electronic device may be provided with structures such as housing structures and electronic device structures associated with electrical components. Electronic device structures such as these may be attached to each other using ultraviolet and visible light curing adhesive. Ultraviolet (UV) and visible (Vis) light curing adhesives may sometimes be referred to herein as UV/Vis light curing adhesive, UV/Vis radiation curing adhesives, ultraviolet and visible light curable adhesives, UV/Vis curable adhesives, or UV/Vis adhesives. 
     A layer of adhesive may be interposed between respective electronic device structures. A light source such as a laser, light-emitting diode, or lamp may generate ultraviolet light for curing the adhesive. 
     The structures may include an ultraviolet-light-transparent structure through which the ultraviolet light passes to illuminate and cure the adhesive. The UV-transparent structure may be formed from one of multiple shots of injection molded plastic in a device structure. For example, the UV-transparent structure may be formed from a first shot of plastic that is transparent to ultraviolet light, whereas a second shot of plastic in the device structure may be formed from a plastic material that is opaque at visible wavelengths. 
     The UV-transparent structure may be partly covered with a coating such as a metal coating to help reflect light onto the adhesive. Metal coatings may also be formed on other structures that are adjacent to the adhesive to enhance light reflections into the adhesive. Perforations in a coating may be used to help pass UV and/or Vis light to the adhesive. 
     Further features, their 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 front perspective view of an illustrative electronic device of the type that may contain structures that are attached to each other with UV/Vis adhesive in accordance with an embodiment. 
         FIG. 2  is a rear perspective view of the electronic device of  FIG. 1  in accordance with an embodiment. 
         FIG. 3  is a side view of a system in which structures are being attached to each other with UV/Vis adhesive by using radiation from a light source that passes through one of the structures in accordance with an embodiment. 
         FIG. 4  is a diagram of equipment for forming plastic structures with desired electromagnetic radiation transmission characteristics in accordance with an embodiment. 
         FIG. 5  is a graph showing illustrative transmission curves that may be associated with different types of plastic in accordance with an embodiment. 
         FIG. 6  is a flow chart of illustrative steps involved in curing adhesive using ultraviolet light that passes through plastic parts such as structures that block visible light while transmitting ultraviolet light in accordance with an embodiment. 
         FIG. 7  is a diagram showing how plastic structures that are suitable for assembling with other structures using UV/Vis adhesive may be formed using multiple shots of injection-molded plastic in accordance with an embodiment. 
         FIG. 8  is a diagram showing how light from an ultraviolet light source may be used to cure adhesive in a scenario in which a part with multiple injection molded shots is being attached to another structure with UV/Vis adhesive in accordance with an embodiment. 
         FIG. 9  is a side view of illustrative structures formed from a two-shot injection molding process showing how UV/Vis radiation for curing a layer of adhesive may pass through one shot of plastic in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of illustrative camera lens mounting structures formed from two shots of plastic in which UV/Vis radiation for curing adhesive passes through one of the shots of plastic in accordance with an embodiment. 
         FIG. 11  is a flow chart of illustrative steps involved with forming injection molded parts from multiple shots of plastic including a shot of plastic that transmits ultraviolet radiation for curing adhesive in accordance with an embodiment. 
         FIG. 12  is a diagram of a system for coating a structure and forming an opening in the coating for facilitating ultraviolet and visible radiation curing of adhesive in accordance with an embodiment. 
         FIG. 13  is a diagram of a system for coating a structure with a patterned coating layer that has openings to receive UV/Vis radiation for UV/Vis adhesive in accordance with an embodiment. 
         FIG. 14  is a cross-sectional side view of a structure with a patterned coating layer showing how UV/Vis radiation for curing adhesive may pass through openings in the patterned coating layer in accordance with an embodiment. 
         FIG. 15  is a cross-sectional side view of an illustrative structure having a patterned coating with an opening that allows ultraviolet radiation to enter the structure to cure adhesive in accordance with an embodiment. 
         FIG. 16  is a cross-sectional side view of a structure having a coating that forms an opening on an end of the structure that allows ultraviolet radiation to enter the structure to cure adhesive in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of a structure having a coating with an opening that receives ultraviolet radiation to cure adhesive and that has a reflective coating to enhance ultraviolet radiation reflections within the structure in accordance with an embodiment. 
         FIG. 18  is a cross-sectional side view of a structure formed over a lower reflective coating and having an upper reflective coating for reflecting ultraviolet radiation within the structures to cure UV/Vis adhesive in accordance with an embodiment. 
         FIG. 19  is a perspective view of a structure that has been coated with a reflective coating and an opaque coating having openings to allow ultraviolet radiation to enter the structure and cure adhesive in accordance with an embodiment. 
         FIG. 20  is a flow chart of illustrative steps involved in forming parts that include patterned coatings having openings through which ultraviolet radiation may pass to cure UV/Vis adhesive in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     It is often desirable to use ultraviolet and visible radiation curing adhesives when assembling structures formed from materials such as plastic, glass, ceramic, metal, and other materials. These type of UV/Vis adhesives may be provided with additives that enhance their sensitivity to electromagnetic radiation (light) at desired wavelengths. For example, UV/Vis adhesives may be formulated that cure upon exposure to ultraviolet and visible light. These UV/Vis adhesives may be cured using light having a wavelength in the range form 100 nm to 700 nm. 
     UV/Vis adhesives may be used to join structures in any suitable equipment. Arrangements in which UV/Vis adhesives are used in assembling parts in an electronic device are sometimes described as an example. This is, however, merely illustrative. Any suitable structures may be attached to one another using UV/Vis adhesives, if desired. 
     An illustrative device of the type that may include electronic device structures joined using UV/Vis adhesives is shown in  FIG. 1 . Electronic device  10  may be a computer such as a computer that is integrated into a display such as a computer monitor, a laptop computer, a tablet computer, a somewhat smaller portable device such as a wrist-watch device, pendant device, or other wearable or miniature device, a handheld device such as a cellular telephone, a media player, a tablet computer, a gaming device, a navigation device, a computer monitor, a television, or other electronic equipment. 
     As shown in  FIG. 1 , device  10  may include a display such as display  14 . Display  14  may be a touch screen that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components or may be a display that is not touch-sensitive. Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. Configurations in which display  14  includes display layers that form liquid crystal display (LCD) pixels may sometimes be described herein as an example. This is, however, merely illustrative. Display  14  may include display pixels formed using any suitable type of display technology. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass or clear plastic. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as speaker port  18 . 
     Peripheral portions of display  14  may be provided with an opaque masking layer. As shown in  FIG. 1 , display  14  may be characterized by a central active region such as active region AA in which an array of display pixels is used in displaying information for a user. Active region AA may be surrounded by an inactive region such as inactive border region IA. Active region AA may have a rectangular shape bordered by rectangular line  20 . Inactive region IA may have a rectangular ring shape that surrounds active region AA (as an example). The underside of the display cover layer in inactive region IA may be covered with an opaque masking layer such as a layer of black ink (e.g., a polymer filled with carbon black). The opaque masking layer may help hide components in the interior of device  10  in inactive region IA from view by a user. 
     If desired, one or more openings may be formed in the opaque masking layer. For example, an opening may be formed in region  22  to form a window for a front-facing camera. Openings may also be formed to accommodate ambient light sensors and other devices. 
     Device  10  may have a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. 
     Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). The periphery of housing  12  may, if desired, include walls. For example, housing  12  may have a peripheral conductive member such as a metal housing sidewall member that runs around some or all of the periphery of device  10  or may have a display bezel that surrounds display  14 . Housing  12  may have sidewalls that are curved, sidewalls that are planar, sidewalls that have a combination of curved and flat sections, and sidewalls of other suitable shapes. One or more openings may be formed in housing  12  to accommodate connector ports, buttons, and other components. 
     As shown in the front perspective view of  FIG. 1 , display  14  may be mounted on the front face of device  10 . As shown in the rear perspective view of  FIG. 2 , device  10  may have a rear housing member such as rear planar housing wall  24 . Wall  24  may be formed from a planar plastic structure, a planar metal structure, a glass layer, ceramics, or other materials. Openings may be formed in rear wall surface  24  for components such as camera  26 . Camera  26  may have a disk-shaped window and associated lenses formed from glass or plastic. A camera window may, for example, be formed from a disk of glass that is mounted in a plastic camera window mounting structure using UV/Vis adhesive. Other structures associated with device  10  may also be assembled using UV/Vis adhesive if desired. For example, adhesive may be used in attaching structures associated with walls for housing  12 , structures associated with the display cover layer in display  14 , structures associated with internal device components, or other electronic device structures in device  10 . 
     To ensure that light having wavelengths within the UV and/or visible portion of the electromagnetic spectrum (for curing adhesive in device  10 ) can reach the adhesive, it may be desirable to form some of the structures in device  10  from materials that are transparent. Device aesthetics may often be enhanced by forming external (or even internal) components from materials that are opaque at visible wavelengths. To ensure that ultraviolet radiation for curing a layer of adhesive may pass through a component that is opaque at visible wavelengths, the component may be formed from a material (such as plastic) that has been configured to absorb light at visible wavelengths (e.g., wavelengths in the visible light range of 390 nm to 750 nm or other suitable visible light range) while transmitting light at ultraviolet wavelengths (e.g., at one or more wavelengths below the 390 nm lower edge of the visible light range, such as some or all wavelengths from 250 nm to 390 nm). This type of component may allow ultraviolet radiation (sometimes referred to as ultraviolet light) to pass through the component to cure adhesive, while exhibiting sufficient opacity at visible wavelengths to appear opaque to a user of device  10  or other viewer of the component. 
     Consider, as an example, the scenario of  FIG. 3 . In the  FIG. 3  example, two structures (structures  28  and  30 ) are being attached to each other using UV/Vis adhesive  32 . 
     Structures  28  and  30  may be portions of device  10  of  FIG. 1  (as an example). For example, structures  28  and  30  may be external or internal housing structures, electrical components, components for forming optical windows, structures for mounting devices such as camera mounting structures or camera window mounting structures, structures associated with buttons and other input devices, a display cover layer, portions of housing  12 , etc. Structure  30  may be formed from plastic, metal, glass, ceramic, other materials, or combinations of these materials. Structure  28  may be formed from a material that has been configured to exhibit transmission in ultraviolet wavelengths and absorption in visible wavelengths. 
     As shown in  FIG. 3 , a light source such as light source  34  may be used to generate ultraviolet light  36 . UV light  36  may, for example, be light with a wavelength of between 100 and 390 nm, light with a wavelength of 365 nm, or other suitable ultraviolet light. UV light  36  may include some light having visible light wavelengths. 
     Structure  28  may be configured to exhibit light absorption at visible wavelengths, so that structure  28  appears opaque to the user of device  10 . Structure  28  may simultaneously be configured to exhibit a low absorption (high transmission) at ultraviolet wavelengths. Structure  28  may, for example, be formed from a polymer with an additive that creates absorption of more than 70% (and therefore transmission at less than 30%) for some or all visible wavelengths (e.g., all wavelengths from 390 to 750 nm, or all wavelengths from 450 to 750 nm) while simultaneously exhibiting a transmission of greater than 70% (and therefore an absorption of less than 30%) at ultraviolet wavelengths of interest (e.g., all wavelengths from 250 nm to 390 nm, all wavelengths from 250 nm to 450 nm, all wavelengths in a 30 nm band or 10 nm band centered on an ultraviolet light curing wavelength of interest such as 365 nm or 385 nm, etc.). 
     When ultraviolet light  36  from light source  34  are applied to structure  28 , however, the relatively high transmission of structure  28  at ultraviolet wavelengths will allow the UV light  36  to pass through structure  28 . When some or all of UV light  36  reaches internal adhesive layer  32 , that UV light  36  can cure adhesive  32 , thereby bonding structures  28  and  30  together. If desired, both structures  28  and  30  may be formed from a plastic (or other material) that is opaque at visible wavelengths and transparent at ultraviolet wavelengths. Adhesive  32  may also be used in joining together three or more different structures. Configurations in which two opposing device structures are being joined by adhesive  32  are described herein as an example. 
     Illustrative equipment for forming structures for an electronic device such as the structures of  FIG. 3  is shown in  FIG. 4 . 
     As shown in  FIG. 4 , equipment such as mixing equipment  42  may be used to combine polymeric materials such as materials  38  with additives  40 . Materials  38  may be liquid polymer precursor materials and/or solid polymers. Additives  40  may be combined with materials  38  using mixing equipment  42  to produce polymer beads or other polymeric material suitable for injection molding (as an example). 
     Injection molding operations with injection molding equipment  44  or other polymer processing operations may be used to form structures such as structure  28  that are transparent at one or more ultraviolet light wavelengths (e.g., wavelengths suitable for curing adhesive  32  of  FIG. 3 ) while being opaque at visible wavelengths. Ultraviolet-light-transparent materials may have a transmission of 50% or more, 70% or more, 80% or more, 90% or more, or 95% or more at ultraviolet light wavelengths of interest (as examples). Visible-light-absorbing materials (opaque materials) may have a transmission of 50% or less, 30% or less, 20% or less, 10% or less, or 5% or less at visible wavelengths (e.g., wavelengths from 390 nm to 750 nm). 
       FIG. 5  is a graph in which illustrative transmission characteristics for structure  28  have been plotted as a function of wavelength λ. As shown by illustrative curve  50 , the polymer material and additives chosen for structure  28  may be configured to exhibit a low transmission in visible light range VIS (i.e., structure  28  may be opaque at visible light wavelengths) while exhibiting high transmission (e.g., transmission of 50% or more, 70% or more, 90% or more, etc.) at wavelengths around 365 nm (e.g., so that light at 365 nm may pass through structure  28  to cure adhesive  32 ). Curve  48  shows how the transmission peak in the ultraviolet range UV may be centered on other wavelengths of interest if desired. As shown by curve  46 , structure  28  may be transparent over a relatively wide range of ultraviolet wavelengths while being opaque at visible wavelengths. Other transmission characteristics may be used for the material of structure  28  if desired. The characteristics represented by curves  46 ,  48 , and  50  of  FIG. 5  are merely illustrative. 
     A flow chart of illustrative steps involved in forming structures such as structure  28  and steps involved in using ultraviolet light that passes through structure  28  to cure adhesive  32  is shown in  FIG. 6 . 
     At step  52 , structures such as structures  28  and  30  of  FIG. 3  may be manufactured. As an example, structure  28  may be formed by combining additives into a polymer to ensure that the polymer has a transmission characteristic of the type shown in  FIG. 5  in which visible light is absorbed more than ultraviolet light (e.g., significantly more such as at least two times more, at least ten times more, etc.). Structures in device  10  such as structure  30  may be formed from the same type of material as structure  28  or from different materials (e.g., metal, plastic, glass, ceramic, multiple materials, etc.). 
     At step  54 , the parts that are to be joined may be mounted to each other using UV/Vis adhesive  32  in liquid form (i.e., adhesive that is in its uncured state). Assembly equipment, portions of the structures that are being joints, and/or assembly personnel may hold the structures in place prior to adhesive curing. 
     At step  56 , a light source such as light source  34  of  FIG. 3  may be used to apply UV radiation  36  to structure  28 . Because structure  28  is transparent to ultraviolet light, UV radiation  36  may pass through structure  28  to illuminate adhesive  32 . By curing adhesive  32  in this way, structures  28  and  30  may be bonded to each other. 
     If desired, injection molding equipment or other processing equipment may be used to form structures that include portions that are transparent to ultraviolet light and portions that are opaque to ultraviolet light. Consider, as an example, a system of the type shown in  FIG. 7 . Initially, process equipment such as injection molding tool  58  may be used in injection molding a first shot of plastic, thereby forming plastic structure  60 . Plastic structure  60  may, for example, form an ultraviolet-light-transparent member (which may be either transparent at visible wavelengths or opaque at visible wavelengths). 
     Following formation of the first shot of plastic, injection molding tool  61  (which may be the same equipment as tool  58  of  FIG. 7  or which may be formed from different equipment) may be used to injection mold a second shot of plastic onto structure  60 . Injection molding tool  61  may, for example, form a second shot of plastic to form plastic structure  62  on plastic structure  60 , as shown in  FIG. 7 . Plastic structure  62  may be formed from a material that need not be transparent to ultraviolet light (and which may be opaque or transparent at visible wavelengths). 
     Using this type of process, a plastic part such as part  64  of  FIG. 7  may be formed that contains at least two different types of plastic. Plastic portion  60  of structure  64  may be transparent to ultraviolet light and plastic portion  62  of structure  64  may be opaque to ultraviolet light. 
     Following formation of two-shot structure  64 , structure  64  may be attached to other device structures such as structure  66  of  FIG. 8  using UV/Vis adhesive  32 . Structure  66  may be a housing structure, an electrical component, or and electronic device structure associated with another component in device  10 . Structure  66  may be formed from plastic, glass, ceramic, metal, other materials, or combinations of these materials. As shown in  FIG. 8 , light source  34  (e.g., an ultraviolet light source) may be used to generate UV light  36 . Uncured liquid UV/Vis adhesive  32  may be placed between structures  64  and  66 . Ultraviolet light  36  may pass through portion  60  of structure  64 , thereby illuminating and curing adhesive  32 . After sufficient illumination with UV radiation  36 , cured adhesive  32  will bond structure  64  to structure  66 . 
     As shown in  FIG. 9 , a two-shot plastic structure such as structure  64  may be formed from thin elongated layers of plastic such as first plastic shot  60  and second plastic shot  62 . Plastic structure  60  may be transparent to ultraviolet light so that UV light  36  can enter structure  60  and illuminate adjacent UV/Vis adhesive  32 , thereby forming an adhesive bond between structure  64  and structure  66 . Plastic structure  62  may be formed from a plastic material that is opaque at ultraviolet light wavelengths and which may also be opaque at visible wavelengths. Structures  60  and  62  may be planar strips or patches of plastic (e.g., layered structures). If desired, structure  62  may be visible to a user of device  10  such as user  68  viewing structure  64  in direction  70 . 
     Another illustrative configuration that may be used for structures such as structure  64  is shown in  FIG. 10 . With the arrangement of  FIG. 10 , structure  64  has been formed from an inner ring (first plastic shot  60 ) and an outer ring (second plastic shot  62 ). Plastic portion  60  may be transparent to ultraviolet light  36 , so that adhesive  32  may be cured when illuminated by UV radiation  36  traveling in direction  72 . Cured adhesive  32  may be used to attach disk-shaped camera window structure  76  to structures  64 . Camera window structure  76  may be formed from clear glass or plastic and may be used to form a window for camera  26  of  FIG. 2  (as an example). Opaque structures such as opaque layer  74  (e.g., a layer of black ink) may be used to block internal housing structures such as structure  60  from view by user  68  observing structure  60  in direction  70 . 
     Illustrative steps involved in forming and using multi-shot plastic injection molded members such as structure  64  are shown in  FIG. 11 . 
     At step  78 , an injection molding tool such as tool  58  of  FIG. 7  may use an injection molding process to form a first shot of plastic such as plastic  60 . Plastic  60  may be transparent to ultraviolet light. 
     At step  80 , an injection molding tool such as tool  61  of  FIG. 7  may be used to form a second shot of plastic such as plastic  62 . Plastic  62  may be opaque to ultraviolet light. Structures  60  and  62  may be opaque or transparent to visible light. 
     Uncured liquid UV/Vis adhesive  32  may be placed between structures to be joined during the operations of step  82 . For example, adhesive  32  may form a layer of liquid adhesive between structures  64  and  66 , as shown in  FIGS. 8 ,  9 , and  10 . 
     During the operations of step  84 , light source  34  may produce UV light  36 . UV light  36  may be applied to structure  64 . UV light  36  that is applied to ultraviolet-light-transparent portion  60  of structure  62  may pass through structure  60  to illuminate and thereby cure adhesive  32 . 
     The process of using UV radiation  36  to cure adhesive  32  may be used in connection with structures that have one or more coating layers. Illustrative systems for forming patterned coating layers on a structure are shown in  FIG. 12 . 
     As shown in  FIG. 12 , a coating tool such as tool  90  may use coating material  88  to apply one or more coatings to uncoated parts  86 . Coating material  88  may be, for example, black ink or other opaque substances. Coatings may be applied using spraying, dipping, physical vapor deposition, chemical vapor deposition, painting, or other suitable fabrication processes. Parts  86  may be formed from materials such as injection molded plastic, glass, ceramic, and other material that are transparent at ultraviolet wavelengths. 
     Following the formation of coated structures  92  by using tool  90  to apply one or more coatings of material  88  on uncoated structures  86 , equipment such as laser-based equipment  94  of  FIG. 12  may be used to selectively remove portions of the deposited coatings (in addition to or instead of leaving portions of structures  92  uncoated during the initial deposition process). Equipment  94  may include a computer-controlled positioner such as positioner  96  that controls the position of laser  98 . By controlling the position of laser  98  using positioner  96  and by controlling the generation of laser light  100 , equipment  94  may create openings such as hole  104  in coating layers such as layer  102  on plastic structure  106 , thereby creating structures such as structure  108  that include one or more patterned coatings such as patterned coating  102 . The bottom surface of structure  106  may also remain uncoated (e.g., to help illuminate adjacent adhesive). Coatings such as coating  102  may be formed from a material that is opaque at selected visible and/or ultraviolet light wavelengths. Examples of materials that may be used for coating  102  include polymers (e.g., black ink) and metals (e.g., metallic paint coatings such as layers of silver paint or aluminum paint, layers of metal deposited using physical vapor deposition equipment, etc.). 
       FIG. 13  shows how coatings may be patterned as part of a deposition process. As shown in  FIG. 12 , coating tool  110  may be provided with coating material  88  and uncoated structure  86  such as plastic structures, glass structures, or other structures that are transparent to ultraviolet light. Coating tool  110  may include equipment for depositing coatings that contain patterned features such as openings (e.g., holes). For example, coating tool  110  may include screen printing equipment, inject printing equipment, pad printing tools, etc. With this type of equipment, coating material  88  may be used to form a patterned coating such as coating  102  with openings such as opening  104  on plastic member  106  of structure  108  (and with an uncoated lower surface in this example). Due to the presence of openings such as opening  104  and the opening associated with the uncoated lower surface of structure  106 , structures such as structure  106  of  FIG. 13  are generally no more than partly coated with coating material. 
     The sizes (e.g., the diameters or other lateral dimensions) of openings such as openings  104  of  FIGS. 12 and 13  may be less than 10 mm, less than 1 mm, more than 1 mm, less than 0.5 mm, less than 0.1 mm, less than 0.05 mm, etc. Smaller openings (e.g., openings of less than 0.05 mm) are sometimes referred to as microperf and may be invisible to the naked eye of a user. Perforations such as microperf openings may therefore be satisfactory for use on exposed surfaces of device  10  where larger holes could be unsightly. If desired, larger openings may also be used on exposed surfaces or may be used on interior surfaces of device  10 . 
       FIG. 14  shows how openings such as openings  104  in patterned layer  102  may be formed on an interior surface of plastic structure  106  of structure  108 . As shown in  FIG. 14 , structure  106  may be mounted on structure  112  using adhesive  32 . Adhesive  32  may initially be provided in liquid form. When light source  34  applies ultraviolet light  36  to structure  106 , UV light  36  may pass through ultraviolet-light-transparent structure  106  and holes  104  in coating  102  to illuminate and cure adhesive  32 . When adhesive  32  is cured in this way, structures  106  and  112  may be bonded to each other. 
     Structure  112  may be, for example, a housing structure, an electronic component, or other structure in device  10  and may be formed from plastic, metal, glass, ceramic, other materials, or combinations of these materials. Structure  106  may be a display cover layer (e.g., a clear glass or plastic layer that serves as a cover for a liquid crystal display module or other display structure), may be a housing structure, may be a part of a component such as an electrical component, or may be other suitable electronic device structure in device  10 . 
     Another illustrative arrangement in which ultraviolet light  36  may be launched into ultraviolet-light transparent member  106  through opening  104  is shown in  FIG. 15 . In an arrangement of the type shown in  FIG. 15 , partial coating layer  102  (e.g., an opaque coating layer) may be placed on the upper surface of ultraviolet transparent structure  106  to help hide structure  106  from view (as an example). UV radiation  36  may be generated using an ultraviolet light source (e.g., source  34 ) such as an ultraviolet laser, an ultraviolet light-emitting diode, or an ultraviolet lamp. UV radiation  36  may scatter from the underside of layer  102  while propagating along the interior of structure  106  and illuminate UV/Vis adhesive  32 . When adhesive  32  is cured by UV radiation  36 , structure  106  will be attached to structure  112 . 
     With the illustrative approach of  FIG. 16 , opening  104  in partial coating  102  on ultraviolet-light-transparent structure  106  has been formed on an end face of structure  106 . Light source  34  ( FIG. 8 ) may launch UV light  36  into structure  106  via one or more side wall openings such as opening  104  of  FIG. 16 , thereby causing UV radiation  36  to propagate along longitudinal axis  114  of structure  106  while exiting the coating opening formed on the lower surface of structure  106  to illuminate and cure adhesive  32 . 
     As shown in  FIG. 17 , coatings on the surface of ultraviolet-light-transparent structure  106  such as coating  102  may be formed from two or more layers of material such as outer coating layer  102 - 1  and inner coating layer  102 - 2 . Coating layer  102 - 2  may be, for example, a metal layer formed from a metallic paint coating or other metal coating. The presence of a metal inner coating on structure  106  may help reduce leakage of ultraviolet light from structure  106  as UV light  36  scatters along the length of structure  106  and illuminates adhesive  32 . Coating layer  102 - 1  may be formed from a layer of black ink or other opaque material (e.g., to reduce external reflections from coating  102 - 2 . 
     As shown by illustrative coating layer  116  of  FIG. 18 , a coating such as coating  116  may be provided underneath ultraviolet-light-transparent structure  106  on upper surface  118  of structure  112 . Coating  116  may be formed from a single layer of material (e.g., an opaque polymer layer or a metal layer) or may be formed from multiple layers (e.g., an outer opaque layer such as layer  102 - 1  and an inner reflective metal layer such as layer  102 - 2 ). The use of layer  116  may help enhance the reflection of UV radiation  36  along the length of structure  106  and may therefore help increase the illumination of UV/Vis adhesive  32  by UV light  36  during curing operations. 
       FIG. 19  is a perspective view of an illustrative configuration that may be used for ultraviolet-light-transparent structure  106  showing how UV radiation  36  may be launched into structure  106  through opening  104  in a portion of coating  102  on the upper surface of structure  106 . Once UV radiation  36  has been coupled into structure  106  through opening  104 , inner coating  102 - 2  may help reflect and guide UV radiation  36  along the length of structure  106 , thereby illuminating adhesive  32 . The process of illuminating adhesive  32  with UV light  36  may cure adhesive  32  to attach structure  106  to structure  112 . 
       FIG. 20  is a flow chart of illustrative steps involved in forming structures such as ultraviolet-light-transparent structures  106  with coatings. 
     At step  120 , injection molding tools, machining equipment, and other equipment may be used in forming structures such as ultraviolet-light-transparent structure  106  and structure  112 . 
     At step  122 , structures such as structure  106  may be partly covered with one or more layers of patterned coatings. For example, coating materials may be deposited and subsequently patterned using laser-based patterning system  94  of  FIG. 12  or other patterning equipment or coating materials may be deposited and patterned at the same time using screen printing, ink-jet printing, or other patterned coating techniques of the type described in connection with  FIG. 13 . Coatings may include one or more layers of material such as metal layers, polymer layers (e.g., polymer-based ink layers), etc. The coatings that are formed in this way may have one or more openings  104 . Openings  104  may be relatively large to accommodate introduction of relatively large beams of ultraviolet light or may be relatively small perforation (e.g., microperf) suitable for use on an exposed (cosmetic) surface in device  10 . An uncoated region may also be formed along the portions of structure  106  that will lie adjacent to adhesive  32 . 
     At step  124 , the structures that have been formed such as coated structure  106  and structure  112  may be assembled using a liquid form of adhesive  32 . Adhesive  32  may be deposited from a nozzle, by spraying, by dipping, or using other application techniques. 
     At step  126 , a light source such as light source  34  may be used to generate UV radiation  36 . UV radiation  36  may be launched into ultraviolet-light-transparent structures  106  through openings  104 . Inside structures  106 , ultraviolet radiation  36  may reflect off of coatings  102  (e.g., metal coatings) and may illuminate adhesive  32 . By illuminating adhesive  32  in this way, adhesive  32  may be cured to attach structures  106  and  112  to each other. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20120806
Publication Date: 20150929
Grant Date: 20150929
Priority Date: 20120806
Inventors: KROGDAHL JAMES R.
Assignee: APPLE INC
CPC Classifications: [{"code": "B29C65/1406", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C2045/1664", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/474", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24008", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1409", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C66/472", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1441", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/1657", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29L2031/764", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1496", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/4845", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/149", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2995/0027", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1435", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/0001", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1122", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2995/0025", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/0001", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C45/0001", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1496", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2045/1664", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/474", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2995/0027", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/149", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/149", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24008", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1409", "inventive": true, "first": false, "tree": "[]"}, {"code": "Y10T428/24008", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/1122", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/4845", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1409", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1441", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1435", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2995/0025", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1435", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/1657", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1496", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/1406", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29C66/1122", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1441", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C2045/1664", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/474", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C66/472", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C45/1657", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C66/73361", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C66/472", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29C65/1406", "inventive": true, "first": true, "tree": "[]"}, {"code": "B29L2031/764", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C65/4845", "inventive": true, "first": false, "tree": "[]"}, {"code": "B29K2995/0027", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29L2031/764", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29K2995/0025", "inventive": false, "first": false, "tree": "[]"}, {"code": "B29C66/73361", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48748528