Laser marking process

Abstract

A manufacturing method for sapphire crystal material is disclosed, including a laser-etched bar code formed into the interior of the sapphire crystal material. The laser-etched bar code may be associated with one or more manufacturing parameters or other manufacturing data. The sapphire crystal may be used to create a cover sheet for use with a display screen of a portable electronic device.

What is claimed is: 
     
       1. A method for manufacturing a cover sheet for a display of a portable electronic device, the method comprising:
 growing a synthetic single-crystal sapphire boule; 
 cutting the synthetic single crystal single-crystal sapphire boule into a brick portion; 
 slicing the brick portion into a single-crystal sheet having an upper surface and a lower surface; 
 forming a laser mark on a portion of the interior of the single-crystal sheet between the upper surface and the lower surface and along a neutral axis of the single-crystal sheet, wherein the laser mark includes encoded information; and 
 after forming the laser mark, polishing the upper and lower surfaces of the single crystal single-crystal sheet to form the cover sheet. 
 
     
     
       2. The method of  claim 1 , wherein the encoded information includes information associated with the growing of the synthetic single-crystal sapphire boule. 
     
     
       3. The method of  claim 1 , wherein the forming of the laser mark includes focusing a laser beam at a location between the upper and lower surfaces to alter an index of refraction of the material at the location. 
     
     
       4. The method of  claim 1 , wherein the forming of the laser mark is performed when one of the upper and lower surfaces are is substantially unpolished. 
     
     
       5. The method of  claim 4 , wherein the upper surface is substantially unpolished and the method further comprising comprises:
 covering at least a portion of the upper surface with a liquid having an index of refraction approximately equal to an index of refraction of the single-crystal sheet; and 
 forming the laser mark while the portion of the upper surface is covered with the liquid. 
 
     
     
       6. The method of  claim 1 , wherein the single-crystal sheet includes an uneven unpolished upper surface and the method further comprises:
 positioning a lens adjacent to the upper surface; and 
 forming the laser mark using the lens. 
 
     
     
       7. The method of  claim 1 , wherein the forming of the laser mark includes etching a bar code into the portion of the single-crystal sheet, wherein the bar code encodes information associated with a manufacturing condition of the growing of the synthetic single-crystal sapphire boule. 
     
     
       8. The method of  claim 1 , wherein the forming of the laser mark includes etching an interior portion along a the neutral axis of the single-crystal sheet between the upper surface and the lower surface. 
     
     
       9. The method of  claim 1 , wherein the laser mark is optically detectable after polishing the upper and lower surfaces. 
     
     
       10. A cover sheet for a portable electronic device comprising:
 a sheet of synthetic single-crystal having an upper surface and a lower surface; and 
 a laser-etched mark marking formed within the synthetic single-crystal sheet between the upper surface and the lower surface and along a neutral axis of the single-crystal sheet, wherein the single-crystal sheet is substantially transparent to light and the marking includes information associated with a manufacturing condition of the synthetic single-crystal sheet. 
 
     
     
       11. The cover sheet of  claim 10 , wherein the marking is located along a neutral axis of the single-crystal sheet the neutral axis of the cover sheet is positioned halfway between the upper surface and the lower surface. 
     
     
       12. The cover sheet of  claim 10 , wherein the laser marking is substantially undetectable to an unaided eye. 
     
     
       13. The cover sheet of  claim 10 , wherein the marking is formed in a direction that is substantially perpendicular to the upper surface. 
     
     
       14. The cover sheet of  claim 10 , wherein the synthetic single-crystal sheet is formed from sapphire. 
     
     
       15. A portable electronic device comprising:
 a housing; 
 a display disposed within the housing; 
 a cover sheet attached to the housing and disposed over the display, the cover sheet including:
 a synthetic single-crystal material having an upper surface and a lower surface, and 
 a laser-etched mark marking within the cover sheet between the upper surface and the lower surface and along a neutral axis of the cover sheet, the marking includes including information associated with a manufacturing condition of the synthetic single-crystal material. 
 
 
     
     
       16. The device of  claim 15 , wherein the manufacturing condition indicates the a repair history of the cover sheet. 
     
     
       17. The device of  claim 15 , wherein the marking is located along a neutral axis of the cover sheet the neutral axis of the cover sheet is positioned halfway between the upper surface and the lower surface. 
     
     
       18. The device of  claim 15 , wherein the manufacturing condition of the synthetic single-crystal material includes one or more of: a manufacturing date, a manufacturing location; or a manufacturing parameter. 
     
     
       19. The device of  claim 15 , wherein the marking is substantially undetectable to an unaided human eye. 
     
     
       20. The device of  claim 15 , wherein the synthetic single-crystal material is sapphire. 
     
     
       21. A method for manufacturing a cover sheet for a display of a portable electronic device, the method comprising:
 forming a laser mark within a chemically-strengthened silicate glass sheet, the laser mark positioned between an upper surface of the silicate glass sheet and a lower surface of the silicate glass sheet and along a neutral axis of the silicate glass sheet, wherein the laser mark includes encoded information; and   after forming the laser mark, polishing the upper and lower surfaces of the glass sheet to form the cover sheet.    
     
     
       22. The method of claim 21, wherein the encoded information includes information associated with a manufacturing condition of the silicate glass sheet.  
     
     
       23. The method of claim 21, wherein the forming of the laser mark includes focusing a laser beam at a location between the upper and lower surfaces to alter an index of refraction of the silicate glass sheet at the location.  
     
     
       24. The method of claim 21, wherein the forming of the laser mark is performed when one of the upper and lower surfaces is substantially unpolished.  
     
     
       25. The method of claim 24, wherein the upper surface is substantially unpolished and the method further comprises:
 covering at least a portion of the upper surface with a liquid having an index of refraction approximately equal to an index of refraction of the silicate glass sheet; and   forming the laser mark while the portion of the upper surface is covered with the liquid.    
     
     
       26. The method of claim 21, wherein the glass sheet includes an unpolished upper surface and the method further comprises:
 positioning a lens adjacent to the upper surface; and   forming the laser mark using the lens.    
     
     
       27. The method of claim 21, wherein the forming of the laser mark includes etching a bar code into an interior portion of the silicate glass sheet, wherein the bar code encodes information associated with a manufacturing condition of the silicate glass sheet.  
     
     
       28. The method of claim 27, wherein the bar code is within an area of 126 μm by 126 μm.  
     
     
       29. The method of claim 21, wherein the laser mark is optically detectable after polishing the upper and lower surfaces.  
     
     
       30. A glass cover sheet for covering a display of a portable electronic device, comprising:
 a chemically-strengthened silicate glass sheet substantially transparent to light and defining an upper surface and a lower surface; and   a laser-etched marking formed within the silicate glass sheet between the upper surface and the lower surface and along a neutral axis of the silicate glass sheet, the laser-etched marking including information associated with a manufacturing condition of the silicate glass sheet.    
     
     
       31. The glass cover sheet of claim 30, wherein the neutral axis of the silicate glass sheet is positioned halfway between the upper surface and the lower surface.  
     
     
       32. The glass cover sheet of claim 30, wherein the laser-etched marking is within an area of 126 μm by 126 μm.  
     
     
       33. The glass cover sheet of claim 32, wherein the laser-etched marking is a bar code.  
     
     
       34. The glass cover sheet of claim 32, wherein the laser-etched marking is a graphic.  
     
     
       35. A portable electronic device comprising:
 a housing;   a display disposed within the housing; and   a cover sheet attached to the housing and positioned over the display, the cover sheet including:
 a chemically-strengthened silicate glass material defining an upper surface and a lower surface, the upper surface defining an exterior surface of the portable electronic device; and 
 a laser-etched marking within the cover sheet between the upper surface and the lower surface and along a neutral axis of the cover sheet, the marking including encoded information associated with a manufacturing condition of the chemically-strengthened silicate glass material.  
   
     
     
       36. The portable electronic device of claim 35, wherein the manufacturing condition indicates a repair history of the cover sheet.  
     
     
       37. The portable electronic device of claim 35, wherein the neutral axis of the cover sheet is positioned halfway between the upper surface and the lower surface.  
     
     
       38. The portable electronic device of claim 35, wherein the manufacturing condition of the chemically-strengthened silicate glass material includes one or more of a manufacturing date, a manufacturing location, or a manufacturing parameter.  
     
     
       39. The portable electronic device of claim 35, wherein the marking is substantially undetectable to an unaided human eye.  
     
     
       40. The portable electronic device of claim 35, wherein the marking is a 2-dimensional pattern of shapes within an area of 126 μm by 126 μm and encoding an identifier of the cover sheet.