PATENT DOCUMENT

Publication Number: US-10537963-B2
Application Number: US-201414575754-A
Country: US
Kind Code: B2

Title: Coated substrate and process for cutting a coated substrate

Abstract:
A system and method of forming a sapphire component. The method may include disposing an absorptive-barrier layer on a first surface of a sapphire substrate, performing a cut in the sapphire substrate using a laser beam incident on the absorptive-barrier layer, and forming and removing molten sapphire from the cut. The method may also include shielding a region of the first surface that is adjacent to the cut from the molten sapphire using the absorptive-barrier layer, and removing the absorptive-barrier layer from the first surface of the sapphire substrate.

Claims:
We claim: 
     
       1. A method for forming a sapphire component, the method comprising:
 selectively applying an absorptive-barrier layer that is confined to a first area of a surface of an optically transparent sapphire substrate; 
 initiating a fusion cut at the first area by:
 irradiating the absorptive-barrier layer with a laser beam; 
 absorbing, by the absorptive-barrier layer, heat energy from the laser beam; and 
 forming a region of molten sapphire at the first area using the heat energy absorbed by the absorptive-barrier layer; 
 
 continuing the fusion cut by advancing the laser beam through the first area to a second area of the surface outside the first area of the optically transparent sapphire substrate; 
 removing molten sapphire from the fusion cut while continuing the fusion cut; and 
 removing the absorptive-barrier layer from the first area. 
 
     
     
       2. The method of  claim 1 , wherein selectively applying the absorptive-barrier layer includes one or more of:
 selectively spraying the absorptive-barrier layer on the first area; 
 selectively printing the absorptive-barrier layer on the first area; 
 selectively painting the absorptive-barrier layer on the first area; 
 selectively dispensing the absorptive-barrier layer on the first area; and 
 selectively adhering the absorptive-barrier layer on the first area. 
 
     
     
       3. The method of  claim 1 , wherein:
 removing molten sapphire from the fusion cut comprises removing molten sapphire using a stream of gas. 
 
     
     
       4. The method of  claim 1 , wherein the absorptive-barrier layer is configured to increase an absorption of the laser beam&#39;s radiation within the optically transparent sapphire substrate to create a localized region of heat energy at the first area. 
     
     
       5. The method of  claim 4 , wherein initiating the fusion cut in the first area comprises using the localized region of heat energy to form the molten sapphire. 
     
     
       6. The method of  claim 1 , wherein the absorptive-barrier layer is formed from a material having a melting temperature that is lower than a melting temperature of the optically transparent sapphire sheet and equal to or greater than 200° C. 
     
     
       7. The method of  claim 1 , wherein the absorptive-barrier layer is formed from a film of opaque polymer material. 
     
     
       8. The method of  claim 1 , wherein the absorptive-barrier layer is formed by selectively coating the first area using a physical vapor deposition (PVD) process. 
     
     
       9. The method of  claim 1 , wherein the absorptive-barrier layer is formed by selectively depositing an ink on the first area. 
     
     
       10. The method of  claim 1 , wherein the absorptive-barrier layer includes an opaque material having a diffuse surface finish. 
     
     
       11. The method of  claim 1 , wherein a thickness of the optically transparent sapphire substrate is equal to or less than 0.5 millimeters. 
     
     
       12. The method of  claim 1 , wherein a thickness of the optically transparent sapphire substrate is between 0.1 millimeters and 3 millimeters. 
     
     
       13. A method of cutting a sapphire component, the method comprising:
 selectively applying an absorptive-barrier layer to a first area of a surface of an optically transparent a sapphire substrate, the absorptive-barrier layer being confined to the first area; 
 initiating a fusion cut through the optically transparent sapphire substrate at the first area by: 
 irradiating the absorptive-barrier layers using a laser beam incident on the absorptive-barrier layer; and 
 transferring heat energy from the laser beam absorbed the first absorptive-barrier layer to the first area to form molten sapphire at the first area; 
 continuing the fusion cut by advancing the laser beam through the first area to a second area of the surface outside the first area of the optically transparent sapphire substrate; and 
 cutting through the optically transparent sapphire substrate at the second area using the laser. 
 
     
     
       14. The method of  claim 13 , wherein cutting through the optically transparent sapphire substrate includes a laser fusion cutting process that comprises:
 irradiating the second area with the laser to form a portion of molten sapphire; and 
 removing the molten sapphire from the optically transparent sapphire substrate using a stream of gas. 
 
     
     
       15. The method of  claim 14 , further comprising:
 shielding the second area from the molten sapphire using a second absorptive-barrier layer applied to the second area.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 61/981,637, filed on Apr. 18, 2014, and entitled “Coated Substrate and Process for Cutting a Coated Substrate,” which is incorporated by reference as if fully disclosed herein. 
    
    
     TECHNICAL FIELD 
     The subject matter of this disclosure relates generally to manufacturing a sapphire part, and in particular to forming a sapphire part using a laser to cut a sapphire substrate having an absorptive and/or barrier layer. 
     BACKGROUND 
     Corundum is a crystalline form of aluminum oxide and is found in various different colors, most of which are generally referred to as sapphire. Sapphire is a hard and strong material with a hardness of 9.0 on the Mohs scale, and, as such, is capable of scratching nearly all other minerals. Because of its hardness and strength, sapphire may be an attractive alternative to other translucent materials like glass or polycarbonate. Sapphire may also be produced in thin sheets and polished to achieve exceptional optical performance. 
     However, in some cases, it may be difficult to process thin, highly polished sheets of sapphire material using traditional techniques. For example, performing a fusion laser cut on a polished sapphire sheet may result in a spatter of molten sapphire deposited on the polished surface. Once cooled and hardened, the spatter may adhere to the polished surface and require further processing to remove. Additionally, in some cases it may be difficult to initiate a laser cut in a sapphire sheet having a highly polished face that does not readily absorb the laser energy. 
     SUMMARY 
     Embodiments described herein are directed to a sapphire component having a layer or multiple layers disposed on one or more surfaces of the sapphire component. The layer(s) may form a barrier and/or an absorptive layer that is configured to facilitate a laser cutting process. For example, the layer(s) may form a barrier that prevents or limits the adhesion of molten sapphire that may be a byproduct of a laser cutting operation or process. Additionally or alternatively, the layer(s) may also function as an absorptive layer that is configured to absorb light emitted from the laser and create a localized heating of the sapphire material, which may facilitate initiation of a laser cut through the sapphire component. 
     One example embodiment may include a method of forming a sapphire component, including disposing an absorptive-barrier layer on a first surface of a sapphire substrate. A cut may be performed in the sapphire substrate using a laser beam incident on the absorptive-barrier layer. As part of the laser cutting operation, molten sapphire may be formed and removed from the cut. The method may also include shielding a region of the first surface that is adjacent to the cut from the molten sapphire using the absorptive-barrier layer. In some embodiments, the absorptive-barrier layer is removed from the first surface of the sapphire substrate after the laser cutting operation is complete. 
     In some embodiments, the absorptive-barrier layer is applied directly to the first surface of the sapphire substrate. For example, the absorptive-barrier layer may be sprayed, printed, and/or painted on the first surface of the sapphire substrate. In some embodiments, the absorptive-barrier layer is formed separately and is adhered to the absorptive-barrier layer on the first surface of the sapphire substrate. In some embodiments, the absorptive-barrier layer is dispensed on the first surface of the sapphire substrate. An absorptive-barrier layer may be formed on one or both sides of a sapphire substrate sheet. 
     In some embodiments, the performing of the cut in the sapphire substrate includes performing a fusion laser cutting process. In some cases, during the fusion laser cutting process, the molten sapphire is removed from the cut using a stream of gas. In some implementations, the absorptive-barrier layer is configured to increase an absorption of the laser beam&#39;s radiation within the sapphire substrate to create a localized region of heat energy at the first surface of the sapphire substrate. The localized region of heat energy may facilitate a laser-cutting operation by helping to melt the sapphire material near the surface of the substrate. In some cases, the cut is initiated in the sapphire using the localized region of heat energy to form a region of molten sapphire. 
     In some embodiments, the disposing of the absorptive-barrier layer includes forming a barrier on the first surface of the sapphire substrate. The barrier may be configured to shield to the first surface from the molten sapphire. The molten sapphire may be transported or sprayed on the surface of the absorptive-barrier layer as a result of a fusion laser cutting process or operation. In some cases, the molten material may be deposited as droplets on the surface of the absorptive-barrier layer and cool and harden. 
     In some embodiments, absorptive-barrier layer is formed from a material having a melting temperature lower than a melting temperature of the sapphire substrate. In some cases, the melting temperature of the material forming the absorptive-barrier layer is equal to or greater than 200 degrees Celsius. In some embodiments, the absorptive-barrier layer is formed from a polymer material. In some embodiments, the absorptive-barrier layer includes a material selected from a polyester sheet, a plastic film, a coating formed by a physical vapor deposition (PVD) process, an ink printing material, and a painted material. In some cases, the absorptive-barrier layer includes an opaque material having a diffuse surface finish. 
     In some example embodiments, the sapphire substrate is irradiated using a laser beam incident on an absorptive-barrier layer that is disposed relative to a first surface of the sapphire substrate. In some cases a cut is initiated in the sapphire substrate by forming a localized region of heat energy using the absorptive-barrier layer. The sapphire substrate may be cut through using the laser after the cut has been initiated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1A  depicts a front view of an example electronic device. 
         FIG. 1B  depicts a rear view of an example electronic device. 
         FIG. 2  depicts a cross-sectional view of a sapphire substrate and an absorptive-barrier layer, according to embodiments. 
         FIG. 3  depicts a flow chart of an example process for forming a sapphire component. 
         FIGS. 4A-4F  depict cross-sectional views of a sapphire substrate and an absorptive-barrier layer undergoing processes of forming a sapphire component for an electronic device as depicted in  FIGS. 1A-B . 
         FIGS. 5A-C  depict cross-sectional view of other example embodiments of a sapphire substrate having one or more absorptive-barrier layers. 
     
    
    
     It is noted that the drawings of the invention are not necessarily to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numbering represents like elements between the drawings. 
     DETAILED DESCRIPTION 
     In general, there may be advantages for a consumer or non-consumer device to include protective coverings, windows, and/or surfaces formed from hard materials such as sapphire. Compared to other optically clear materials like traditional silicate glass, sapphire offers improved scratch resistance and strength. However, thin sheets of optically clear sapphire may be difficult to manufacture using some traditional techniques. In particular, it may be difficult to initiate a laser cut on a sheet that is both very thin and highly polished. Additionally, laser cutting a polished sheet may affect the surface finish of a polished surface, which may require further lapping and/or polishing to restore. As discussed herein, in accordance with various embodiments, sapphire components can be manufactured by laser cutting a sapphire substrate having an absorptive-barrier layer that may reduce or eliminate some issues related to manufacturing thin sapphire components. 
     In some embodiments, a sapphire substrate may have an absorptive-barrier layer formed on a surface that facilitates a laser-based manufacturing processes. In particular, the absorptive-barrier layer may facilitate a laser fusion cutting operation. In some instances, during a fusion cutting operation, a laser beam is used to heat and partially melt a portion of the sapphire substrate. A directed stream of gas may be used to remove molten sapphire leaving a void or depression in the sapphire substrate. The efficiency and edge finish produced by a fusion cut may be superior to other types of laser cutting techniques, including, for example, physical etching, ablation laser cutting, or laser scribing. 
     However, in some circumstances it may be difficult to use a fusion cutting process on a thin, highly polished sapphire sheet. In particular, during a fusion cutting operation, the molten sapphire that is removed by the gas stream may form a flume of spatter on the surface of the sapphire substrate. When the molten sapphire cools and hardens, it may adhere to the surface and become difficult to remove. If the sapphire substrate has already been polished, further lapping or surface polishing may need to be performed to remove the spatter produced by the fusion cut. As described in some embodiments below, an absorptive-barrier layer disposed on a sapphire substrate may shield or protect the surface of the substrate from molten sapphire that may be created during a fusion cut. In some cases, the absorptive-barrier layer is configured to have a melting point that is sufficiently high to form an effective barrier to the molten sapphire. Additionally, the melting point and thermal properties of the absorptive-barrier layer may be configured to minimize or prevent the material from receding away from the laser cut thereby exposing a portion of the sapphire surface adjacent to the cut. 
     Additionally, in some cases, it may be difficult to initiate a fusion cut on a sapphire substrate that has been polished to a fine surface finish (e.g., polished surface). For example, a sapphire substrate having a fine surface finish may be too transparent to sufficiently diffuse or in-couple the laser light and generate the heat required to initiate a laser cut. As described in some embodiments below, an absorptive-barrier layer disposed on a sapphire substrate may facilitate a laser cutting operation by increasing the absorption of the laser beam near the surface of the substrate. In some cases, the absorptive-barrier layer facilitates the formation of a localized region of heat energy at the first surface of the sapphire substrate and helps to initiate a laser cut in the sapphire material. In some cases, the initiated cut may be used to advance a laser cut through or partly through the sapphire material. In some cases, once the laser cut has been initiated using the absorptive-barrier layer, the laser cut may be advanced to regions of the sapphire substrate that are not covered by the absorptive-barrier layer, 
     The systems and techniques described herein can be used to facilitate a laser cutting operation to manufacture a sapphire component or part. While the following examples are provided with respect to a laser fusion cutting operation, the systems and techniques may also be applicable to other types of laser-based operations including, for example, laser ablation, laser etching, laser stress cracking, and the like. Additionally, although the embodiments and processes discussed herein relate to a sapphire substrate, it is understood that additional materials having similar characteristics (e.g., high melting temperature, high hardness, optically transparent, etc.) as sapphire may be undergo similar processes. In accordance with various embodiments described below, a sapphire substrate having an absorptive-barrier layer may be used to produce a thin sheet sapphire component having an exceptional surface finish. 
     In accordance with various embodiments,  FIGS. 1A-B  depict a device having multiple hard protective sheets on the exterior of the device. In the present example, the protective sheets are formed from one or more sapphire components, which may provide outstanding scratch resistance and enhance the mechanical integrity of the device. A protective sheet may also function as an optically transmissive window and provide visibility to underlying components, such as display screens or graphical elements. In a typical implementation, both the optical and mechanical properties of the protective sheets may be important to perception of quality and performance of the device. 
     As shown in  FIG. 1A , the device  10  includes protective cover sheet  11  formed from a sapphire component and used as an optically transmissive protective layer. The cover sheet  11  is typically attached to the device  10  using an optically transmissive adhesive or other bonding technique. In this example, the cover sheet  11  is attached using a pressure sensitive adhesive (PSA) film. The cover sheet  11  may be attached to the face of the display screen  20  and protect the display screen  20  from scratches or other physical damage. The display screen  20  may include a liquid crystal display (LCD), organic light emitting diode (OLED) display, or similar display element. Because the cover sheet  11  overlays the display screen  20 , optical clarity, a polished surface finish, material thickness, and physical strength may be useful aspects of the cover sheet&#39;s  11  functionality, alone or in conjunction with other such aspects. The cover sheet  11  may also be attached to, or be integrated with, a transparent electronic sensor that overlays the display screen  20 . In some cases, the electronic sensor covers the entire display screen  20  and is used as the main input device for the user. In some implementations, the cover sheet  11  may be integrated with a touch sensor configured to detect finger or stylus touches on the surface of the cover sheet  11 , a force sensor configured to determine a force exerted on the cover sheet  11 , or other sensors that detect interactions with the cover sheet  11 . 
     In some embodiments, the cover sheet  11 , depicted in  FIG. 1A , is formed from a sapphire component having an overall thickness equal to or less than 3 mm. In some embodiments, the sapphire component may have a thickness that is greater than 3 mm. Typically, the overall thickness of the cover sheet  11  is less than 1 mm, although this thickness may vary between devices and/or embodiments. In some cases, the overall thickness is less than 0.3 mm. In one non-limiting example, the overall thickness of the sapphire component is approximately 0.25 mm, and may be less. For very thin sheets of sapphire material (e.g., approximately 0.5 mm or less), the addition of an absorptive-barrier layer in accordance with the some embodiments may improve laser cutting and manufacturing processes. 
     The cover sheet  11  may be formed from a sapphire material that includes alumina, corundum, or other forms of aluminum oxide (Al 2 O 3 ). Accordingly, references to sapphire or a sapphire material may incorporate or encompass one or more forms aluminum oxide. In some embodiments, the cover sheet  11  may be formed from a single sheet of sapphire material or, alternatively, be formed from a laminate material made from multiple layers and having at least one layer formed from a sheet of sapphire. In the present example, one side of the cover sheet  11  is printed with a solid, opaque border around a perimeter portion. The center portion of the cover sheet  11  remains optically transmissive. The printed side of the cover sheet  11  is typically the side that is opposite the external face of the device  10  to prevent the printed portion from becoming scratched or damaged. The side of the cover sheet  11  that is external to the device may include an anti-reflective or other type of coating to enhance the optical properties of the cover sheet  11 . 
     As shown in  FIG. 1A , the front surface of the device  10  also includes a button sheet  12  used to protect the surface of the control button  22 . In this example, the button sheet  12  is formed from a sapphire component and is used as an optically transmissive protective layer. The button sheet  12  protects the surface of a control button  22  and allows visibility of any graphical elements that are printed on the control button  22 . In some cases, it is not necessary that the button sheet  12  be optically transmissive. For example, the button sheet  12  may be opaque and itself printed with a graphical element or symbol. In this case, the button sheet  12  is a flat sheet, but in other embodiments, the button sheet  12  may be formed as a contoured or curved surface. 
     The button sheet  12  may enhance the mechanical strength of control button  22 , which is used as an input to the device  10 . In the present example, the control button  22  includes a tactile switch which is operated by depressing the control button  22 . The control button  22  may also include or be associated with an electronic touch sensor, such as a capacitive touch sensor or biometric sensor. The button sheet  12  may be attached directly to a housing of the control button  22  and may, alternatively be attached or integrated with the electronic touch sensor of the control button  22 . Similarly, a sapphire component can be used as a protective cover for a variety of input mechanisms, including, a slide, wheel, key, and the like. 
     In some embodiments, the button sheet  12  depicted in  FIG. 1A  is formed from a sapphire component having an overall thickness equal to or less than 3 mm. In some embodiments, the sapphire component may have a thickness that is greater than 3 mm. Typically, the thickness of the sapphire component is less than 1 mm. In some cases, the overall thickness of the sapphire component is less than 0.3 mm. In one non-limiting example, the overall thickness is approximately 0.25 mm, and may be less. Similar to the cover sheet  11 , the button sheet  12  may be formed from a single sheet of sapphire material or, alternatively, be formed from a laminate material having at least one layer formed from a sheet of sapphire. In some cases, the button sheet  12  is formed from the same material as the cover sheet  11 , although this is not necessary. One or both sides of the button sheet  12  may also be printed or coated to enhance the optical properties of the sapphire part. 
     As shown in  FIG. 1B , the back surface of the device  10  is protected by a back sheet  13 . Similar to the cover sheet  11 , the back sheet  13  is also formed from a sapphire component and is used as an optically transmissive protective layer. In this case, the back sheet  13  provides visibility of graphical elements printed on the back face of the device  10 . Also similar to the cover sheet  11 , the back sheet  13  may be formed from a single sheet of sapphire material or, alternatively, be formed from a laminate material having at least one layer formed from a sheet of sapphire. In this case, the back sheet  13  covers the entire back of the device  10 , except for the area near the camera lens  24 . A separate sapphire component may be used to protect the camera lens  24 . In an alternative embodiment, the back sheet  13  also covers the camera lens  24  and a separate sapphire component is not used. 
     In this example, the protective cover sheets ( 11 ,  12 ,  13 ) are formed from sapphire sheet components made from a crystalline form of alumina (Al2O3), also referred to as corundum.  FIGS. 1A-B  are provided by way of example, and a sapphire component may be used to form a protective cover over virtually any exterior surface. The sapphire sheet may range in thickness from 3 mm to 0.1 mm and may have a hardness of approximately 9.0 on the Mohs scale, although alternative embodiments may have sheet(s) of different thickness(es). As discussed above, any one of the protective cover sheets ( 11 ,  12 ,  13 ) may be formed as a laminate of multiple sheets of material and may also be coated with one or more materials to enhance the optical or mechanical properties of the part. In some cases, it may be beneficial to form all of the protective cover sheets ( 11 ,  12 ,  13 ) from the same sapphire substrate to simplify the manufacturing process. However, different types of sapphire substrates may be used for each cover sheet, depending on the optical and/or mechanical properties desired for each piece. 
     As shown in  FIGS. 1A-B , the device  10  is a portable electronic device. The device  10  may be any one of a variety of devices utilizing a hard substrate as a covering, window, and/or surface. For example, the device  10  may be a portable electronic device, such as a mobile phone, portable media player, wearable electronic device, health monitoring device, and/or other portable appliance. Similar types of protective covers may be applied to other electronic devices, including, for example, tablet computers, notebook computers, and various wearable devices. Additionally, the protective covers may be applied to other types of devices including non-electronic devices, such as mechanical watches which utilize an optically transmissive face over the dial. Alternatively, the protective covers may be integrated with any device that includes a hard exterior surface, particularly if the surface includes a display screen, camera, or other optical element. 
     As discussed above with respect to  FIGS. 1A-B , various components (e.g., cover sheet  11 , button sheet  12 , and back sheet  13 ) of an electronic device may be formed from sapphire material, which may include various forms of aluminum oxide. As shown in  FIG. 2  and discussed in detail below, various components of electronic device  10  may be formed from a sapphire substrate  100 . That is, and as discussed herein with respect to  FIGS. 2, 3, and 4A -F, sapphire substrate may undergo a plurality of processes (e.g., laser cutting) in order to form one or more sapphire components used as a protective sheet for electronic device  10 . Additionally, as discussed herein, to improve processing of sapphire substrate  100  and ultimately improve the sapphire component formed form sapphire substrate  100 , an absorptive-barrier layer  102  may be disposed on a first surface  104  of sapphire substrate  100  prior to processing. 
     As shown in  FIG. 2 , and discussed herein, sapphire substrate  100  may include artificially grown corundum used to form a sapphire component for electronic device  10 . One or more surfaces of sapphire substrate  100  may be subjected to one or more surface treatments, such as grinding, lapping, and polishing to achieve a fine surface finish on the surface  104 . Additionally, the sapphire substrate  100 , as shown in  FIG. 2 , may undergo pre-processing procedures prior to the addition of the absorptive-barrier layer  102 , and the subsequent processes (e.g., laser cutting). In a non-limiting example, sapphire substrate  100  may be sliced from a boule, ground down to a desired thickness, and/or polished to provide the desired surface finish. In some cases, the sapphire substrate  100  has been processed to achieve a final surface finish. 
     As shown in  FIG. 2 , an absorptive-barrier layer  102  is disposed on first surface  104  of sapphire substrate  100 . In one example, the absorptive-barrier layer  102  may be formed from a polymer material to substantially shield first surface  104  of sapphire substrate  100  during processing of sapphire substrate  100 . In some cases, the absorptive-barrier layer  102 , as shown in  FIG. 2 , may be formed from a polyester sheet, plastic film, paint (e.g., ink), curable opaque material (polymer spray), or other suitable material that may substantially form a protective barrier and/or an optically absorptive layer on first surface  104  of sapphire substrate  100 . In some cases, the absorptive-barrier layer  102  is produced using a lamination process, a physical vapor deposition (PVD) process, printing process, painting process, or other technique for forming the absorptive-barrier layer  102  on the sapphire substrate  100 . 
     In some cases, the absorptive-barrier layer  102  may have a melting temperature that is lower than a melting temperature of sapphire substrate  100 . In a non-limiting example, the material forming the absorptive-barrier layer  102  may include a melting temperature of approximately 200° C., and the melting temperature of the sapphire substrate  100  may be approximately 2000° C. In some cases, the absorptive-barrier layer  102  has a melting temperature greater than or equal to 200° C. and less than or equal to the melting temperature of the sapphire substrate  100 . 
     The material used to form absorptive-barrier layer  102  may also be tailored to facilitate a laser-based operation performed on sapphire substrate  100 . In a non-limiting example, and as discussed herein, the material forming the absorptive-barrier layer  102  may have particular optical characteristics that facilitate or improve a laser cutting process performed on sapphire substrate  100 . In one example, absorptive-barrier layer  102  may be substantially opaque with a diffuse surface finish. In particular, the absorptive-barrier layer  102  may be substantially opaque to the wavelength of light produced by a cutting laser. Generally, the transparency characteristic (e.g., opacity) of the absorptive-barrier layer  102  may be tailored to the operational characteristics or perimeters (e.g., wavelength, power, pulse length, spot size) of the laser beam used to cut the sapphire substrate  100 . In some cases, the surface finish of the absorptive-barrier layer  102  may also be tailored to facilitate laser absorption. That is, absorptive-barrier layer  102  may include a substantially rough or abrasive surface finish to aid in laser absorption for processing and/or cutting sapphire substrate  100 , as discussed herein with respect to  FIGS. 4A-F . 
     As discussed herein, an absorptive-barrier layer  102  having particular optical qualities may be disposed on sapphire substrate  100  and facilitate absorption of a laser beam to initiate a laser cut in the sapphire substrate  100 . In particular, the absorptive-barrier layer  102  may absorb laser radiation and form a localized region of heat energy near the surface of the sapphire substrate and facilitate melting or vaporization of the sapphire in that region. For very thin sheets of sapphire material (e.g., approximately 0.5 mm or less), the addition of an absorptive-barrier layer having suitable optical properties may substantially improve the laser cutting process. In one non-limiting example, the overall thickness of the sapphire component may be approximately 0.25 mm. In another non-limiting example, the overall thickness of the sapphire component may be less than 0.25 mm. 
       FIG. 3  depicts an example process for forming a sapphire component using an absorptive-barrier layer and a laser-based cutting operation. Specifically,  FIG. 3  is a flowchart depicting one example process  300  for forming a sapphire component. In some cases, the sapphire component may be used to form one or more protective sheets in an electronic device, as discussed above with respect to  FIGS. 1A-B . 
     In operation  302 , one or more absorptive-barrier layers are disposed on a sapphire substrate. In one example, at least one absorptive-barrier layer is disposed on a first (optical) surface of the sapphire substrate. The method of disposing the absorptive-barrier layer on the first surface of the sapphire substrate may be dependent, at least in part, on the material used in the absorptive-barrier layer. In non-limiting examples, the disposing of the absorptive-barrier layer may include, applying, spraying, printing, painting, adhering and/or dispensing the absorptive-barrier layer on the first surface of the sapphire substrate. In the non-limiting example where the absorptive-barrier layer is adhered to the sapphire substrate, an adhesive layer may be applied to the first surface of the sapphire substrate to adhere the absorptive-barrier layer to the sapphire substrate. The disposing of the absorptive-barrier layer, in operation  302 , may also include forming an opaque or light-absorptive material on or within the absorptive-barrier layer. The opaque or light-absorptive material formed on or within the disposed absorptive-barrier layer may facilitate a laser-based cutting operation. In some cases, the absorptive-barrier layer is formed from a material that has the desired opacity or light-absorptive properties without the addition of another material. As discussed in more detail below, the absorptive-barrier layer may shield or protect the first surface of the sapphire substrate during subsequent processing of the sapphire substrate. 
     In some implementations of operation  302 , a plurality of absorptive-barrier layers may be disposed relative to the sapphire substrate. More specifically, an absorptive-barrier layer may be disposed on a first surface of the sapphire substrate, and another absorptive-barrier layer may be disposed on a second surface of the sapphire substrate, opposite the absorptive-barrier layer disposed on the first surface. Additionally, multiple absorptive-barrier layers may be disposed relative to each other and both layers disposed on a surface of the sapphire substrate. 
     With respect to example process  300 , in some implementations, the sapphire substrate is provided already having the absorptive-barrier layer already formed on one or more surfaces. That is, in some implementations, operation  302  may be optional due to the manner in which the material is provided or handled by upstream manufacturing processes. For example, in some cases, the absorptive-barrier layer may be formed on the surface of the sapphire substrate shortly after a final polishing process to reduce the chance of scratching or damage due to handling or manipulation of the sapphire substrate. In some cases, the absorptive-barrier layer may protect one or more surfaces of the sapphire substrate before and after the laser-cutting operation  304 . 
     In operation  304 , a cut may be performed on the sapphire substrate. The cut may be performed using a laser beam incident on the absorptive-barrier layer. In one example, a fusion laser cutting process may be performed on the sapphire substrate to cut the sapphire substrate to form sapphire components for an electronic device. In some cases, during the cutting process of operation  304 , the absorptive-barrier layer may absorb energy from the incident laser beam and form a localized region of heat energy. As previously mentioned, a localized concentration of energy may aid in initiating a cut in the sapphire substrate. Once the cut is initiated, the laser may advance the cut through the material and/or along a cutting path to form a profile cut. In some implementations, the absorptive-barrier layer is only utilized during the initiation of the cut, and the laser may advance the cut to a region of the sapphire substrate that is not coated or covered by the absorptive-barrier layer. In some embodiments, the cut does not advance all the way through the sapphire substrate and may form a groove, channel, or other type of recess in the surface of the sapphire substrate. 
     In operation  306 , an amount of molten sapphire may be formed and removed from the cut in the sapphire substrate. In one example, a fusion cutting process is performed in operation  304 . As part of the fusion cutting process, an amount of molten sapphire may be formed within the cut of the sapphire substrate. The molten sapphire may then be removed from the cut of the sapphire substrate using a jet or stream of gas that is directed to the portion of the substrate being cut. In some cases, a jet or stream of gas may propel or blow out the molten sapphire in order to create a void or cut in the sapphire substrate. 
     In some instances, removal of the molten sapphire from the cut using a jet or stream of air may propel the molten sapphire into a plume of small droplets. In some cases, the droplets of molten sapphire land back on the substrate in a region near the cutting laser. As discussed previously, if the molten sapphire is deposited on a polished surface of the sapphire substrate, further processing may be required to remove the droplets and restore the sapphire substrate to an appropriate level of surface finish. As discussed below with respect to operation  308 , use of an absorptive-barrier layer disposed on a surface of the sapphire substrate may prevent this undesirable result. 
     In operation  308 , a region of the first surface of the sapphire substrate may be shielded or protected from the molten sapphire formed and removed from the cut in operation  306 . In one example, the absorptive-barrier layer disposed on the first surface of the sapphire substrate may form a barrier and/or may shield a region of the first surface of the sapphire substrate positioned adjacent to the cut from molten sapphire removed from the cut using the stream of gas. In some cases, all or nearly all of the molten sapphire removed from the cut and projected upward by the gas stream may not be deposited on the first surface of the sapphire substrate due to the shielding provided by the absorptive-barrier layer. Additionally, the molten sapphire removed from the cut of the sapphire substrate may, instead, be deposited on the absorptive-barrier layer until further processing of the absorptive-barrier layer and/or sapphire substrate. 
     In some cases, the absorptive-barrier layer is formed from a material having a melting point and thermal properties that aid or enable the processes performed in operation  308 . In particular, the melting point and thermal properties of the absorptive-barrier layer may help the absorptive-barrier layer maintain coverage of the first surface of the sapphire substrate. In some cases, the absorptive-barrier layer resists melting when proximate to the cutting laser beam. For example, the absorptive-barrier layer may have a melting point and/or thermal properties help to prevents or reduces the chance that the absorptive-barrier layer will recede away from the region adjacent to the laser cut. 
     In operation  310 , the absorptive-barrier layer may be removed from the first surface of the sapphire substrate. More specifically, the absorptive-barrier layer, and any previously molten sapphire droplets deposited on the absorptive-barrier layer may be removed from the first surface of the sapphire substrate. Similar to methods of disposing of the absorptive-barrier layer in operation  302 , the removal process may be dependent, at least in part, on the material used in the absorptive-barrier layer. In non-limiting examples, the absorptive-barrier layer may be removed by polishing, buffing, grinding, dissolving and/or washing the absorptive-barrier layer, including the molten sapphire, from the first surface of the sapphire substrate. In some cases, an ultrasonic cleaning process is used to remove the absorptive-barrier layer. The removal of the absorptive-barrier layer, including any sapphire droplets, from the sapphire substrate may result in the formation of a final sapphire component that may be substantially free from cosmetic, structural and/or optical defects caused by molten sapphire formed on the first surface of the sapphire substrate. As discussed above with respect to  FIGS. 1A-B , the sapphire component may be used to form one or more of the protective sheets of an electronic device. 
     Turning to  FIGS. 4A-4F , sapphire substrate  100  and absorptive-barrier layer  102  are shown undergoing various operations that may be performed in accordance with process  300  of  FIG. 3 . It is understood that similarly numbered components may function in a substantially similar fashion. Redundant explanation of these components has been omitted for clarity. 
     As shown in  FIG. 4A , absorptive-barrier layer  102  may be disposed on first surface  104  of sapphire substrate  100 , as discussed herein. In some cases, the absorptive-barrier layer  102  may include an opaque, polymer material that may be applied directly to and/or positioned on first surface  104  of sapphire substrate  100 . Additionally as discussed herein, the polymer material forming absorptive-barrier layer  102  may include a melt temperature (e.g., 200° C.) that may be less than the melting temperature (e.g., 2000° C.) of sapphire substrate  100 . The disposing of the absorptive-barrier layer  102 , as shown in  FIG. 4A , may correspond to operation  302  of  FIG. 3 . 
     Turning to  FIGS. 4B and 4C , a cut  106  (see,  FIG. 4C ) may be performed in the sapphire substrate  100 , as discussed herein. Specifically,  FIGS. 4B and 4C  show the progression of performing cut  106  in the sapphire substrate  100  using a laser beam  108 . The performing of the cut  106  in sapphire substrate  100 , as shown in  FIGS. 4B and 4C , may correspond to operation  304  of  FIG. 3 . In a non-limiting example, as shown in  FIG. 4B , a laser  110  may be utilized to perform a fusion laser cutting process for performing the cut  106  within sapphire substrate  100 . Laser  110  may include one of a variety of lasers that are suitable for providing a laser beam  108  capable of forming cut  106  in sapphire substrate  100 , as discussed herein. In some embodiments, the laser cut is performed using a fiber laser that configured to produce a laser beam at wavelengths centered at approximately 1070 nm and pulse durations ranging from 0.2 to 10 ms. In some cases, the laser is configured to produce a laser beam at a power ranging from 10 watts to 150 watts average power (with a maximum of 1,500 watts of maximum power). Additionally as shown, and discussed below in detail, fusion laser system including fusion laser  110  may also include a gas delivery nozzle  112  positioned adjacent fusion laser  110 . Gas delivery nozzle  112  may provide a jet or stream of gas  116  for removing portions of sapphire substrate  100  from cut  106  during operation of fusion laser  110 , as discussed herein. 
     Fusion laser  110  may provide a laser beam  108  incident on and/or through absorptive-barrier layer  102 , as discussed herein. Due in part to the optical characteristics, material composition, and/or lower melting temperature of the absorptive-barrier layer  102 , the absorptive-barrier layer  102  may be configured to increase an absorption of radiation produced by the laser beam  108 . The increased absorption may create a localized region or concentration of heat energy  114  at first surface  104  of sapphire substrate  100 , which may facilitate an initial cut in the sapphire substrate  100 . In a non-limiting example, as shown in  FIGS. 4B and 4C , and discussed herein, sapphire substrate  100  may be formed from a polished sapphire sheet. As a result of the polished properties of sapphire substrate  100 , photons of laser beam  108  may substantially pass through a region of bare sapphire  100  without sufficiently heating and melting the sapphire substrate  100 . However, as previously discussed, this may be avoided by using an absorptive-barrier layer  102  disposed or positioned on first surface  104 . 
     Due, in part, to the opaque optical properties and/or the low melting temperature of the polymer material forming absorptive-barrier layer  102 , absorption of radiation produced by the laser beam  108  may be increased by using an absorptive-barrier layer  102 . Subsequently, in some cases, the absorptive-barrier layer  102  may ultimately transfer the radiation of laser beam  108  to create a localized region of heat energy  114  at first surface  104 , and ultimately through sapphire substrate  100  (see,  FIG. 4C ). As shown in  FIG. 4C , this localized region of heat energy  114  may initiate the cut in sapphire substrate  100 . 
     As shown in  FIG. 4C , the performing of the cut  106  using laser  110  may also result in the formation of droplets of molten sapphire  118  from the cut  106 . More specifically, while forming the cut  106  in sapphire substrate  100 , droplets of molten sapphire  118  may be formed from remnants of sapphire substrate  100  that are melted and/or removed from the cut  106 . In some cases, the gas delivery nozzle  112  may provide a stream of gas  116  to the region near the cut  106  to remove or push molten sapphire  118  out of the cut  106 . An amount of molten sapphire  118  may be propelled by the stream of gas  116  out of the cut  106  and away from sapphire substrate  100 . In some cases, some amount of molten sapphire  118  that is removed from cut  106  is deposited on the absorptive-barrier layer  102 . The forming and removing of molten sapphire  118 , as shown in  FIG. 4C , may correspond to operation  306  in  FIG. 3 . 
     As shown in  FIG. 4D , cut  106  may be completely formed in sapphire substrate  100  and the sapphire substrate  100  may be removed from fusion laser  110 . As discussed herein with respect to  FIG. 4C , previously molten sapphire  118  that was deposited on the absorptive-barrier layer  102  may remain as hardened sapphire droplets on absorptive-barrier layer  102 . As discussed herein, absorptive-barrier layer  102  may form a barrier on first surface  104  of sapphire substrate  100  to shield first surface  104  from molten sapphire  118 . More specifically, absorptive-barrier layer  102  may shield a region of first surface  104  positioned adjacent cut  106  from molten sapphire  118 , such that molten sapphire  118  may not contact, and/or adhere to first surface  104  during and/or after forming the cut  106  in sapphire substrate  100 . The shielding of the first surface  104  of the sapphire substrate  100 , as shown in  FIG. 4D , may correspond to operation  308  in  FIG. 3 . 
     Finally, as shown in  FIGS. 4E and 4F , absorptive-barrier layer  102  may be removed from first surface  104  of sapphire substrate  100 . In one example, as shown in  FIG. 4E , absorptive-barrier layer  102  and (previously) molten sapphire  118  (shown in phantom) may be removed from first surface  104  of sapphire substrate  100 , such that molten sapphire  118  never contacts and/or bonds to first surface  104 . Continuing the non-limiting example above, the opaque, polymer material forming absorptive-barrier layer  102 , and the molten sapphire  118  contacting or bonded to absorptive-barrier layer  102 , may be removed by using a polishing or ultrasonic cleaning technique. The removing of absorptive-barrier layer  102  and molten sapphire  118  formed on absorptive-barrier layer  102 , as shown in  FIGS. 4E and 4F , may correspond to operation  310  in  FIG. 3 . 
     As shown in  FIG. 4F , a sapphire component  200  may be formed from sapphire substrate  100 , and may be included in a component of electronic device  10 . In one example, as shown in  FIG. 4F , where sapphire substrate  100  includes a large sapphire sheet, a plurality of sapphire components  200  may be formed using the process and/or operations discussed herein with respect to  FIGS. 3 and 4A -F. As previously mentioned, the sapphire component  200  may be used to form one or more protective sheets (e.g., cover sheet  11 , button sheet  12 , and back sheet  13 ) in an electronic device  10  (see,  FIGS. 1A-B ). 
     As previously mentioned, the absorptive-barrier  102  may serve as both a shielding protective layer and an optically absorptive layer. However, in some alternative embodiments, the absorptive-barrier layer  102  may only perform one of these two functions. For example, in some cases, the absorptive-barrier layer  102  be applied to sapphire substrate  100  solely for its optical absorptive qualities. In this scenario, the absorptive-barrier layer  102  may be disposed on sapphire substrate  100  to facilitate absorption of optical (e.g., laser) energy and facilitate a laser cut in the sapphire substrate  100 . However, the absorptive-barrier layer  102  may not necessarily provide substantial shielding from molten sapphire. 
     In one non-limiting example, the absorptive-barrier layer  102  may be formed from an ink that is painted or sprayed onto first surface  104 . The ink forming absorptive-barrier  102  may form a thin, opaque material layer on first surface  104  of sapphire substrate  100 , that may facilitate absorption of the laser beam to initiate the laser cut in the sapphire substrate  100 , as discussed herein. The ink alone may not necessarily shield and/or prevent molten sapphire  118  from contacting or bonding to first surface  104  during the cutting process. However, the ink coating may be combined with another coating or layer to provide shielding or protection from molten sapphire. In some cases, the ink coating is used alone and there is not an additional protective layer applied to the surface of the substrate. In some cases, the enhanced optical properties of the surface due to the ink layer facilitates absorption of the laser beam, and helps to initiate and stabilize the laser cut within sapphire substrate  100 . In some cases, the amount or spread of the molten sapphire  118  may be reduced and/or may be more easily removed from cut  106  by gas delivery nozzle  112  with a reduced amount of scattering or spatter. 
     The absorptive-barrier layer may be configured in a variety of example embodiments, as discussed herein. More specifically, a plurality of absorptive-barrier layers may be disposed or positioned on the sapphire substrate prior to performing a cut, as discussed herein. The inclusion of multiple absorptive-barrier layers on sapphire substrate may provide further support and/or may further aid in the shielding of the sapphire substrate from molten sapphire during the cutting process, as discussed herein. Additionally, the inclusion of multiple absorptive-barrier layers on sapphire substrate may aid in the formation of a localized region of heat energy at the first surface of the sapphire substrate and may help initiate a laser cut in the sapphire substrate. It is understood that similarly numbered components may function in a substantially similar fashion. Redundant explanation of these components has been omitted for clarity. 
       FIG. 5A  depicts a cross-sectional view of sapphire substrate  500  according to additional embodiments. As similarly discussed herein with respect to  FIGS. 2 and 4A -F, sapphire substrate  500  may include absorptive-barrier layer  502   a  disposed and/or positioned on first surface  504  for forming a barrier for sapphire substrate  500 . Distinct from sapphire substrate in  FIGS. 2 and 4A -F, sapphire substrate  500  in  FIG. 5A  includes a distinct or second absorptive-barrier layer  502   b  formed on a second surface  520  of sapphire substrate  500 . More specifically, sapphire substrate  500  may include a distinct absorptive-barrier layer  502   b  disposed on second surface  520  positioned opposite first surface  504  of sapphire substrate  500 . As shown in  FIG. 5A , absorptive-barrier layers  502   a ,  502   b  disposed on opposite surfaces of sapphire substrate  500  may be formed from the same material. In a non-limiting example, absorptive-barrier layers  502   a ,  502   b  may be formed from an opaque, polymer material, as similarly discussed herein with respect to  FIGS. 2 and 4A -F. However, and as discussed herein, it is understood that absorptive-barrier layers  502   a ,  502   b  may be formed from distinct materials having similar characteristics or properties (e.g., opaque material, melting temperature lower than sapphire melting temperature, rough or abrasive surface, etc.). Absorptive-barrier layers  502   b  may be disposed on second surface  520  of sapphire substrate  500  using any suitable disposing technique discussed herein, where the disposing technique may be dependent, at least in part, on the material used in absorptive-barrier layer  502   b.    
     Similar to  FIG. 5A ,  FIG. 5B  depicts a cross-sectional view of sapphire substrate  500  including absorptive-barrier layers  203   a ,  503   b . However, distinct from  FIG. 5A ,  FIG. 5B  shows absorptive-barrier layer  503   b  disposed or positioned on absorptive-barrier layer  503   a . More specifically, absorptive-barrier layer  503   a  may be disposed on first surface  504  of sapphire substrate  500 , as discussed herein, and absorptive-barrier layer  503   b  may be disposed directly on absorptive-barrier layer  503   a , and may be positioned adjacent first surface  504  of sapphire substrate  500 . As shown in  FIG. 5B , absorptive-barrier layers  503   a ,  503   b  may be formed from different materials. That is, in another non-limiting example, absorptive-barrier layers  503   a  disposed on first surface  504  of sapphire substrate  500  may be formed from a polyester sheet and absorptive-barrier layers  503   b  disposed on absorptive-barrier layer  503   a  may be formed from a plastic film. In another example, a first layer  503   a  may provide substantial protection or shielding from any molten sapphire that may be produced during a laser cut. The second layer  503   b  may provide substantial optical absorption to facilitate absorption of the laser and help initiate a laser cut. Thus, the two layers  503   a ,  503   b  may together provide a barrier layer having the desired optical properties to facilitate a laser-based cutting operation. Absorptive-barrier layers  503   b  may be disposed on absorptive-barrier layer  503   a  using any suitable disposing technique discussed herein, where the disposing technique may be dependent, at least in part, on the material used in absorptive-barrier layer  503   b.    
       FIG. 5C  shows a cross-sectional view of sapphire substrate  500  according to another embodiment. As shown in  FIG. 5C , absorptive-barrier layer  524  may be disposed or positioned on first surface  504  of sapphire substrate using an adhesive  522 . More specifically, absorptive-barrier layer  524  may be adhered to sapphire substrate  500  via adhesive  522  applied to first surface  504 . Adhesive  522  may be used to adhere absorptive-barrier layer  524  to sapphire substrate  500  where absorptive-barrier layer  524  is made from a material that may not naturally adhere to the first surface  504 . In a non-limiting example where absorptive-barrier layer  524  includes a pre-manufactured plastic film, adhesive  522  can be applied directly to first surface  504  of sapphire substrate  500 , and absorptive-barrier layer  524  (e.g., plastic film) may be adhered or bonded to adhesive  522 . Once bonded to adhesive  522 , absorptive-barrier layer  524  may be disposed or positioned on first surface  504  prior to performing a cutting process on sapphire substrate  500 , as discussed herein. 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not target to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Metadata:
Filing Date: 20141218
Publication Date: 20200121
Grant Date: 20200121
Priority Date: 20140418
Inventors: LI, MICHAEL M.
RICHTER, ANTHONY J.
SUN, YULEI
MOLINA, RAUL A.
Assignee: APPLE INC
CPC Classifications: [{"code": "B23K26/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2101/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/142", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/0622", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/54", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2101/36", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/009", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/009", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/009", "inventive": true, "first": true, "tree": "[]"}, {"code": "B23K26/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/142", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K2103/54", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K2101/34", "inventive": false, "first": false, "tree": "[]"}, {"code": "B23K26/0622", "inventive": true, "first": false, "tree": "[]"}, {"code": "B23K26/38", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54321205