PATENT DOCUMENT

Publication Number: US-9221289-B2
Application Number: US-201213560791-A
Country: US
Kind Code: B2

Title: Sapphire window

Abstract:
Methods for creating sapphire windows are provided herein. In particular, one embodiment may take the form of a method of manufacturing sapphire windows. The method includes obtaining a polished sapphire wafer and applying decoration to the sapphire wafer. The method also includes cutting the sapphire wafer into discrete windows. In some embodiments, the cutting step comprises laser ablation of the sapphire.

Claims:
The invention claimed is: 
     
       1. A method of manufacturing sapphire windows comprising:
 obtaining a polished sapphire wafer comprising material for forming a set of discrete windows; 
 applying decoration to the polished sapphire wafer; and 
 after applying decoration, cutting the polished sapphire wafer into the set of discrete windows. 
 
     
     
       2. The method of  claim 1 , wherein applying decoration to the sapphire wafer comprises printing ink onto a first side of the polished sapphire wafer. 
     
     
       3. The method of  claim 2 , further comprising applying an oleophobic coating to a second side of the polished sapphire wafer. 
     
     
       4. The method of  claim 2 , wherein the ink defines a boundary for each of the discrete windows. 
     
     
       5. The method of  claim 2 , wherein the ink is cut during the cutting step. 
     
     
       6. The method of  claim 2 , wherein the ink is not cut during the cutting step. 
     
     
       7. The method of  claim 1 , wherein the cutting step comprises laser ablation of the sapphire wafer. 
     
     
       8. The method of  claim 7 , wherein the laser ablation comprises pulsing a laser. 
     
     
       9. The method of  claim 7 , wherein the sapphire wafer is cut to provide an angled edge to each discrete window of the set of discrete windows. 
     
     
       10. The method of  claim 1 , further comprising applying an oleophobic coating to the wafer. 
     
     
       11. The method of  claim 1 , further comprising applying an IR coating to the wafer. 
     
     
       12. The method of  claim 1 , further comprising blunting at least one edge of each discrete window of the set of discrete windows. 
     
     
       13. The method of  claim 1 , further comprising:
 growing a sapphire boule; 
 coring the sapphire boule to form a sapphire core; 
 slicing the sapphire core into wafers; 
 lapping the sapphire wafers; 
 polishing the sapphire wafers to provide the polished sapphire wafers. 
 
     
     
       14. The method of  claim 13 , wherein slicing the sapphire core into wafer comprises using a laser to slice the sapphire core. 
     
     
       15. A method of manufacturing sapphire windows comprising:
 growing a sapphire boule; 
 coring the sapphire boule to form a sapphire core; 
 slicing the sapphire core into sapphire wafers, each sapphire wafer comprising material for forming a set of discrete windows; 
 lapping the sapphire wafers; 
 polishing the sapphire wafers to provide polished sapphire wafers; 
 cutting the polished sapphire wafers into the set of discrete windows using a laser; and 
 applying an ink mask to each discrete window of the set of discrete windows. 
 
     
     
       16. The method of  claim 15 , further comprising operating the laser in a pulsed manner to create an angled edge. 
     
     
       17. The method of  claim 15 , further comprising operating the laser in a manner to form a vertical edge. 
     
     
       18. The method of  claim 15  further comprising applying at least one of:
 an IR coating; and 
 an oleophobic coating. 
 
     
     
       19. A method of manufacturing sapphire windows comprising:
 extruding a sapphire member comprising material for forming a set of discrete windows; 
 applying decoration to the sapphire member; 
 grinding an edge of the sapphire member; 
 subsequent to the applying of the decoration to the sapphire member, cutting the sapphire member using a laser to form the set of discrete windows; and 
 polishing each discrete window of the set of discrete windows. 
 
     
     
       20. The method of  claim 19  further comprising applying to the polished windows at least one of:
 an ink mask; 
 an oleophobic coating; or 
 an IR coating. 
 
     
     
       21. The method of  claim 19 , wherein the extruding step results in an elongate sapphire member having an axial profile approximating a size of the resulting windows.

Description:
TECHNICAL FIELD 
     The present application generally relates to camera windows and more particularly relates to sapphire camera windows. 
     BACKGROUND 
     Mobile electronic devices are ubiquitous in today&#39;s society. From cell phones to tablet computers, they can be found in pockets, purses, and briefcases, and are used in both personal and business settings. Generally, the devices include a visual display output. In some cases, display may perform double-duty by providing the visual output and receiving touch input. Often, these devices also include cameras and other input devices. Both the display screens and camera covers are typically made of glass. 
     In processing the glass for use as a camera cover or a display screen, a large sheet of glass is initially cut into squares by a scribe and break process before each of the cut squares are ground into a desired shape. Chamfers may be added to the individual glass pieces and a chemical strengthening process may be performed to help fortify the glass pieces. Subsequently, each individual glass piece is lapped, polished and decorated to finally produce the glass cover or screen. The process is lengthy and includes many steps, most of which are performed on an individual basis rather than in a batch. Despite all the processing, the glass remains susceptible to damage and scratches, chips and cracks in the glass diminish the ability of the device to perform its intended purposes. 
     SUMMARY 
     One embodiment may take the form of a method of manufacturing sapphire windows. The method includes obtaining a polished sapphire wafer and applying decoration to the sapphire wafer. The method also includes cutting the sapphire wafer into discrete windows. In some embodiments, the cutting step comprises laser ablation of the sapphire. 
     Another embodiment may take the form of a method of manufacturing sapphire windows that includes growing a sapphire boule, coring the sapphire boule to form a sapphire core and slicing the sapphire core into wafers. Additionally, the method includes lapping the sapphire wafers, polishing the sapphire wafers for provide polished sapphire wafers and dicing the sapphire wafer into discrete windows using a laser. The method also includes applying an ink mask to the discrete windows. 
     Yet another embodiment may take the form of a method of manufacturing sapphire windows that includes extruding a sapphire member and grinding an edge of the sapphire member. Additionally, the method includes slicing the sapphire member using a laser to form windows and polishing the windows. 
     While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following Detailed Description. As will be realized, the embodiments are capable of modifications in various aspects, all without departing from the spirit and scope of the embodiments. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a front side of an example electronic device having a sapphire cover. 
         FIG. 1B  illustrates a back side of the example electronic device of  FIG. 1A . 
         FIG. 2  is a flowchart illustrating an example method for processing sapphire windows for use in the electronic device of  FIGS. 1A and 1B . 
         FIG. 3A  is a flowchart illustrating another example method for processing sapphire windows for use in the electronic device of  FIGS. 1A and 1B . 
         FIG. 3B  illustrates a sapphire wafer with an ink mask defining discrete windows. 
         FIG. 3C  is an enlarged view of a discrete window cut from the sapphire wafer showing the ink mask. 
         FIG. 3D  illustrates another sapphire wafer with an ink mask defining discrete cover windows. 
         FIG. 4A  is a cross-sectional view taken along line IV-IV in  FIG. 3D  showing cuts made to the sapphire wafer to create the discrete cover windows. 
         FIG. 4B  is a side view of a cover window having a vertical edge. 
         FIG. 4C  is a side view of a window having an angled edge. 
         FIG. 4D  illustrates a window having a fully chamfered edge. 
         FIG. 5A  is a cross-sectional view taken along line V-V in  FIG. 1A  illustrating a gasket to secure a window within the device housing. 
         FIG. 5B  is a cross-sectional view taken along line V-V in  FIG. 1A  illustrating the window compressing the gasket when installed. 
         FIG. 5C  is a cross-sectional view taken along line V-V in  FIG. 1A  illustrating a heat activated film for securing the window within the device housing. 
         FIG. 6  is a flow chart illustrating yet another example method for processing sapphire windows for use in the electronic device of  FIGS. 1A and 1B . 
     
    
    
     DETAILED DESCRIPTION 
     Conventionally, sapphire has not been a viable alternative for glass or plastic surfaces of electronic devices. This is due in part to the cost of obtaining and difficulty of processing the sapphire. In particular, sapphire is relatively rare and expensive. Additionally, due to the hardness of the sapphire, conventional processes may not be effective or may result in faster wearing of tools and significantly increased processing times. Methods for creating sapphire windows are described herein that achieve processing efficiencies to, in part, make the replacement of glass or plastic members of electronic devices feasible, whereas previously such replacement would be at least cost prohibitive. Generally, the sapphire window may be C-plane sapphire, although other orientations may be implemented as well. The C-plane is typically more available commercially and provides a good level of hardness. 
     One embodiment may take the form of a method that includes cutting through the sapphire using a laser. That is, the laser may have sufficient power to cut through the sapphire. To this point, commercially available lasers have not been able to perform this task with sufficient efficiency, primarily due to insufficient power. Specifically, the laser may be capable of operating at or near 50 Watts, although some embodiments may utilize higher or lower power lasers. Additionally, in some embodiments, the laser power may be dynamically adjusted to suit a particular purpose. Moreover, the laser may operate in or near the IR band of the electromagnetic spectrum and may be capable of pulsing in or near the pico second time frame. In other embodiments, the laser may operate with pulse lengths from the millisecond to the femtosecond range. The use of the laser provides for a faster cut over conventional techniques, such as CNC grinding used for glass but that still yields a sufficiently clean edge. Further, the laser is able to cut with precision so that a single wafer of sapphire may yield more similar sized windows than a glass wafer that is cut using conventional techniques. 
     The sapphire wafer may be pre-polished. The laser cutting does not disturb the polished surface. As such, decoration, such as ink patterning, may be applied to the sapphire wafer rather than after the windows are cut. Additionally, other treatments such as application of an oleophobic layer may be applied to the sapphire wafer prior to cutting. Performing such steps on the sapphire wafer rather than on discrete sapphire windows allows for faster and more efficient throughput as there are fewer processing steps and less handling of the windows. 
     In some embodiments, additional processing may be performed after the windows are cut, however. For example, the laser may be used to further shape the edges of the windows. In one embodiment, the edge of the windows may be given chamfers or may be blunted by the laser. Further, in some embodiments, an oleophobic layer or other layers may be applied after the windows have been cut. 
     Referring to  FIGS. 1A and 1B , an example electronic device  100  is illustrated. In particular,  FIG. 1A  illustrates a front side  102  of the electronic device  100  and  FIG. 1B  illustrates a back side  104  of the electronic device. The front side  102  may include a display  106  with a sapphire cover window  108 . In some embodiments, the window  108  may take the form of a sapphire sheet, a sapphire sheet with a glass laminate layer, or other suitable material, through which a visual output of the device  100  is output. Additionally, the window  108  may be configured to receive input from users via sensors, such as capacitive sensors. The back side  104  of the electronic device  100  includes a camera  110  with a cover window  112 . As with the window  108  of the front side  102 , the cover window  112  may take any suitable form, such sapphire. 
     The illustrated electronic device  100  is a smart phone, such as the iPhone® made by Apple, Inc. It should be appreciated, however, that the present techniques may be implemented in the manufacture of a variety of different devices including but not limited to media players, tablet computers, cameras, cell phones, and so forth. As such, the present discussion and accompanying drawings should be understood as non-limiting examples. Moreover, although the present examples discuss sapphire, it should be appreciated that it may be possible to implement the present techniques with materials other than sapphire. Further, the term “window” as used herein should not be limited to applications where visible light traverses the sapphire. Indeed, window may refer to transparency of visible and non-visible electromagnetic radiation, such as radio frequency (RF) transmittance for antennas. 
     The processing steps for creation of windows for use in the device  100  may be streamlined to achieve efficiencies that may reduce the cost of using sapphire as the window material. In particular,  FIG. 2  is a flowchart illustrating an example method  120  for processing sapphire windows. Initially, sapphire boule is grown and the boule is cored (Blocks  122  and  124 ). The boule may be grown in accordance with contemporary sapphire growth techniques. The coring of the sapphire boule yields an elongated sapphire member. The sapphire core is sliced into wafers (Block  126 ). The wafers are lapped (Block  128 ) and polished (Block  130 ) before being diced by a laser (Block  132 ) to form discrete windows. The windows may then individually be coated and masked (Block  134 ). The coating and masking may include, for example, providing an oleophobic coating and an ink mask. 
     Referring again to step  122 , conventional sapphire growth processes may include, for example, an edge defined film-fed growth process, a Kryopolous method, a vertically directed crystallization method, or other suitable method. The boule may be shaped into a core that may generally take the form of a cylindrical core by trimming the boule in any suitable manner before slicing the core to form the wafers. The shaping and slicing of the core may be performed by a high power laser in some embodiments, while in other embodiments, conventional tools may be used to shape and/or slice the core into wafers. Utilizing the laser to cut the core into wafers may provide faster processing time, or more cost effective process than when conventional cutting tools are used. The wafers may be lapped and polished using two-sided or single-sided lapping and polishing techniques. That is, one or both sides of the wafer are lapped and polished individually or simultaneously to provide opposing smooth surfaces. 
     Cutting the lapped and polished sapphire wafer with the laser results in a higher yield of windows than conventional cutting techniques. This is due in part to the high level of precision of the laser and its ability to make fine cuts. Additionally, the laser cutting does not damage or mar the surfaces of the wafer or the windows, thus enabling the pre-dicing polishing to be the only polishing step. In conventional processing, a polishing step is commonly performed after dicing. 
     The subsequent treatment of the individual windows may include the application of an oleophobic layer to a first side of the window and an ink mask on the second side of the window. The first side of the window may generally be the side of the window that will be exposed to and accessible to a user of the device  100 . The second side, therefore, is generally the non-exposed side and inaccessible to the user, although, in some embodiments, the opposite may be feasible and desirable using the laser cutting methods. The ink mask may be a dark or black ink that surrounds, or provides boundaries to the windows. In some embodiments, additional treatments may be applied to the window such as an IR coating for the cover window  112 . 
       FIG. 3A  is flowchart illustrating another method  140  for processing the sapphire to create windows. As with the method of  FIG. 2 , a sapphire boule may be grown and a core may be cut from the boule (Block  142  and  144 ). The core may be sliced into wafers (Block  146 ) which may be lapped and polished as above (Block  148  and  150 ). However, in contrast to the method of  FIG. 2 , the wafer may be decorated and treated prior to dicing the wafer (Block  152 ). The wafer may then be diced using the laser (Block  154 ). 
     As may be appreciated, the decoration and treatment at the wafer level may result in significant processing cost and time savings relative to the method illustrated in  FIG. 2 . In particular, all of the windows may be decorated and treated while still part of the wafer. The decoration therefore is applied to all the windows at once. There is no need to individually collect, orient and secure each window for discrete treatment and/or decoration. When dicing the windows from the wafer, the laser may be configured to cut through the decoration in some embodiments. The decoration will sustain little or no damage due to being cut through by the laser. In other embodiments, the decoration may be applied to the wafer such that it will not be cut by the laser. 
       FIG. 3B  illustrates an example sapphire wafer  160 . The sapphire wafer  160  has been masked with an ink mask that defines discrete windows  162  that may be cut from the wafer  160  and used in the device  100 , for example as camera windows. Generally, the windows  162  may be densely packed on the wafer  160 . That is, the distance between the respective windows  162  may be small. This small distance is limited only by the width of cut achievable by a laser used to dice the wafer  160  into discrete windows.  FIG. 3C  is an enlarged view of a discrete window  162  cut from the wafer  160  and showing an ink mask  163 .  FIG. 3D  illustrates another wafer  164  which has been masked to define discrete cover windows  166  which may be cut from the wafer  164 . Generally, the ink mask  165  may be limited to periphery edges of the cover windows  166 , although it should be appreciated that in some embodiments this may not be the case. As with the wafer  160  of  FIG. 3B , the cover windows  166  are densely packed. 
       FIG. 4A  is a cross-sectional view taken along line IV-IV of the wafer  164  of  FIG. 3C . Generally, the wafer  164  may be cut by a laser in using one of a variety of techniques to provide a desired edge for a particular use. In particular, for example, the wafer  164  may be cut to provide vertical edges  168  for a cover window. Alternatively, the wafer  164  may be cut to have angled edges  169  for use as a camera window. To achieve the vertical or straight edges  168 , the laser ablation process may utilize a laser of a different pulse length. In contrast, to achieve the angled edges  169 , the laser may be pulsed and may move in a repetitive motion to remove material a layer at a time as it proceed to cut through the wafer. 
       FIG. 4B  illustrates a side view of the cover window  166  after it has been cut. As may be appreciated, the corner edges may be further processed to provide a rounded or chamfered corner.  FIG. 4C  illustrates a camera window  162  after it has been cut from the wafer. The angled edge  169  may be blunted by cutting vertically along the dashed line  170 . The blunting may be performed be the laser or other conventional machining tool. The edge  169  may further be cut to provide a fully chamfered edge  162  as shown in  FIG. 4D . It should be appreciated that the laser cutting allows vertical sidewalls to be created as well. Specifically, the vertical sidewall may result from an initial cut of a window from a wafer without further processing, for example. 
     The windows  162 ,  166  may be secured within a housing  174  of the device  100  in any suitable manner.  FIG. 5A  illustrates the window  162  being secured within the housing  174  of the device  100  using a rubber gasket  176 . Specifically, the window  162  is pushed into the housing  174  and compresses the gasket  176 , as shown in  FIG. 5B . Thus, the rubber gasket  176  secures the window  162  as well as provides a cushion for the window. Further, the gasket  176  may help to center the window  162  within an aperture or within the housing. In other embodiments, a heat activated film or pressure sensitive adhesive may be used to secure the window.  FIG. 5C  illustrates the window  162  pressed into the film  178 . The heat activated film  178  adheres to both the housing  174  and the window  162  to secure the window  162  within or to the housing  174 . 
       FIG. 6  is a flowchart illustrating yet another method  180  for processing sapphire to create windows. In the method  180 , an EFG process is implemented to form the sapphire. Specifically, the sapphire is grown in a near net shape crystal rod (Block  182 ). The rod may then be profile grinded to the desired size and shape (Block  184 ). The rod is sliced to form the windows (Block  186 ). The windows are lapped (Block  188 ) and polished (Block  190 ) before coating and masking the windows (Block  192 ). The coating and masking steps may include those previously discussed such as providing an IR coating, an oleophobic coating, and an ink decoration. As the sapphire rod may be extruded to approximate the desired shape of the window, several steps may be saved over other methods. Specifically, there is no coring and no dicing of wafers. As such, processing costs and time may be reduced. 
     The foregoing describes some example embodiments of sapphire windows and processing of sapphire windows. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the embodiments. In particular, certain processes and/or treatments described above with respect one embodiment may be implemented with other embodiments. Accordingly, the specific embodiments described herein should be understood as examples and not limiting the scope thereof.

Metadata:
Filing Date: 20120727
Publication Date: 20151229
Grant Date: 20151229
Priority Date: 20120727
Inventors: PREST CHRISTOPHER D.
SHUKLA ASHUTOSH Y.
MEMERING DALE N.
VASANTHAKUMAR VASHIST
YAN VINCENT
JOHANNESSEN THOMAS
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B1/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "B41M5/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B1/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B1/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "B41M5/24", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 48808531