Laser cutting of display glass compositions

Abstract

The present invention relates to a laser cutting technology for cutting and separating thin substrates of transparent materials, for example to cutting of display glass compositions mainly used for production of Thin Film Transistors (TFT) devices. The described laser process can be used to make straight cuts, for example at a speed of >1 m/sec, to cut sharp radii outer corners (<1 mm), and to create arbitrary curved shapes including forming interior holes and slots. A method of laser processing an alkaline earth boro-aluminosilicate glass composite workpiece includes focusing a pulsed laser beam into a focal line. The focal line is directed into the glass composite workpiece, generating induced absorption within the material. The workpiece and the laser beam are translated relative to each other to form a plurality of defect lines along a contour, with adjacent defect lines have a spacing of 0.1-20 microns.

What is claimed is: 
     
         1 . A method of laser cutting a continuous ribbon of glass drawn from a draw tower, the method comprising:
 drawing the continuous ribbon of glass from the draw tower; and   laser cutting the continuous ribbon of glass drawn from the draw tower by forming a series of defect lines along a laser cut line, wherein:
 each defect line of the series of defect lines extends through an entire thickness of the continuous ribbon of glass, and 
 each defect line of the series of defect lines is formed by focusing a pulsed laser beam into a laser beam focal line oriented along a beam propagation direction and directed into the continuous ribbon of glass, the laser beam focal line generating an induced absorption within a material of the continuous ribbon of glass such that the induced absorption produces the defect line along the laser beam focal line within the continuous ribbon of glass. 
   
     
     
         2 . The method of  claim 1 , wherein a glass sheet is separated from the continuous ribbon of glass along the laser cut line. 
     
     
         3 . The method of  claim 1 , wherein each defect line of the series of defect lines is formed by translating the pulsed laser beam relative to the continuous ribbon of glass along the laser cut line. 
     
     
         4 . The method of  claim 1 , wherein the series of defect lines extends across an entire width of the continuous ribbon of glass from the draw tower. 
     
     
         5 . The method of  claim 1 , wherein the series of defect lines extends along the laser cut line adjacent a bead of the continuous ribbon of glass drawn from the draw tower. 
     
     
         6 . The method of  claim 5 , wherein the bead is separated from the continuous ribbon of glass along the laser cut line. 
     
     
         7 . The method of  claim 1 , wherein the pulsed laser beam comprises pulse bursts with at least 2 pulses per pulse burst. 
     
     
         8 . The method of  claim 1 , wherein the pulsed laser beam has a laser power of 10 W-150 W and produces pulse bursts with at least 2 pulses per pulse burst. 
     
     
         9 . The method of  claim 8 , wherein the pulsed laser beam has laser power of 10 W-100 W and produces pulse bursts with at least 2-25 pulses per pulse burst. 
     
     
         10 . The method of  claim 8 , wherein the pulsed laser beam has laser power of 25 W-60 W, and produces pulse bursts with at least 2-25 pulses per burst and a periodicity between each defect line in the series of defect lines is 2-10 microns. 
     
     
         11 . The method of  claim 8 , wherein (i) the pulsed laser beam has laser power of 10 W-100 W, and (ii) the continuous ribbon of glass and the pulsed laser beam are translated relative to one another at a rate of at least 0.25 m/sec. 
     
     
         12 . The method of  claim 8 , wherein (i) the pulsed laser beam has laser power of 10 W-100 W; and (ii) the continuous ribbon of glass and the pulsed laser beam are translated relative to one another at a rate of at least 0.4 m/sec. 
     
     
         13 . The method of  claim 10 , wherein the periodicity is from about 0.5 micron to about 3 microns. 
     
     
         14 . The method of  claim 1 , wherein a periodicity between each defect line in the series of defect lines is from about 0.1 microns to about 20 microns. 
     
     
         15 . The method of  claim 14 , wherein the periodicity is from about 0.5 micron to about 3 microns. 
     
     
         16 . The method of  claim 14 , wherein the periodicity is from about 2 micron to about 20 microns. 
     
     
         17 . The method of  claim 14 , wherein the continuous ribbon of glass comprises a laminated sheet comprising multiple layers. 
     
     
         18 . The method of  claim 17 , wherein each of the multiple layers comprises a different material property. 
     
     
         19 . The method of  claim 17 , wherein the draw tower is a double-isopipe draw tower comprising two or more isopipes, each of the two or more isopipes provides glass for a different layer of the laminated sheet. 
     
     
         20 . The method of  claim 1 , wherein a pulse duration is in a range of between greater than about 1 picosecond and less than about 100 picoseconds. 
     
     
         21 . The method of  claim 20 , wherein the pulse duration is in a range of greater than about 5 picoseconds to less than about 20 picoseconds. 
     
     
         22 . The method of  claim 1 , wherein a burst repetition rate of the pulsed laser beam is in a range of about 1 kHz to about 4 MHz. 
     
     
         23 . The method of  claim 22 , wherein the burst repetition rate is in the range of about 10 kHz to about 650 kHz. 
     
     
         24 . The method of  claim 1 , wherein each pulse of the pulsed laser beam has an average laser burst energy measured at the continuous ribbon of glass greater than 40 microJoules per mm thickness of the continuous ribbon of glass. 
     
     
         25 . The method of  claim 1 , wherein pulses of the pulsed laser beam are produced in bursts of at least two pulses separated by a duration in a range of about 1 nsec to about 50 nsec, and wherein a burst repetition rate of the pulsed laser beam is in a range of about 1 kHz to about 650 kHz. 
     
     
         26 . The method of  claim 25 , wherein the pulses produced in bursts are separated by a duration of about 20 nsec. 
     
     
         27 . The method of  claim 1 , wherein the pulsed laser beam has a wavelength selected such that the continuous ribbon of glass is substantially transparent at the wavelength. 
     
     
         28 . The method of  claim 1 , wherein the laser beam focal line has a length in a range of about 0.01 mm to about 100 mm. 
     
     
         29 . The method of  claim 1 , wherein the laser beam focal line has a length in a range of about 0.1 mm to about 10 mm. 
     
     
         30 . The method of  claim 1 , wherein the laser beam focal line has a length in a range of about 0.1 mm to about 1 mm. 
     
     
         31 . The method of  claim 1 , wherein the laser beam focal line has an average spot diameter in a range of about 0.1 micron to about 5 microns. 
     
     
         32 . The method of  claim 1 , wherein the induced absorption produces subsurface damage up to a depth less than or equal to about 100 microns within the continuous ribbon of glass. 
     
     
         33 . The method of  claim 1 , wherein laser cutting through the entire thickness of the continuous ribbon of glass along the laser cut line facilitates separation of the continuous ribbon of glass along a surface defined by the laser cut line to form a separated surface, and wherein the induced absorption produces an Ra surface roughness of the laser cut line and the separated surface of less than or equal to about 0.5 micron. 
     
     
         34 . The method of  claim 1 , wherein laser cutting through the entire thickness of the continuous ribbon of glass along the laser cut line facilitates separation of the continuous ribbon of glass along a surface defined by the laser cut line to form a separated surface, and wherein the induced absorption produces particles on the separated surface with an average diameter of less than 3 microns. 
     
     
         35 . The method of  claim 1 , wherein the continuous ribbon of glass has a thickness in a range of about 0.01 mm to about 5 mm. 
     
     
         36 . The method of  claim 1 , wherein the continuous ribbon of glass and the pulsed laser beam are translated relative to each other at a speed in a range of about 1 mm/sec to about 3400 mm/sec. 
     
     
         37 . The method of  claim 1 , wherein the continuous ribbon of glass comprises an alkaline earth boro-aluminosilicate glass composite. 
     
     
         38 . The method of  claim 1 , wherein laser cutting is performed with the continuous ribbon of glass at a temperature around an annealing temperature of the continuous ribbon of glass. 
     
     
         39 . The method of  claim 38 , wherein the continuous ribbon of glass comprises at least two layers having at least two different respective annealing temperatures, and wherein laser cutting is performed with the continuous ribbon of glass at a temperature between the at least two different respective annealing temperatures. 
     
     
         40 . The method of  claim 38 , wherein the continuous ribbon of glass comprises at least two layers, and wherein laser cutting is performed with the continuous ribbon of glass above the annealing temperature of the continuous ribbon of glass. 
     
     
         41 . The method of  claim 1 , further comprising separating a glass sheet from the continuous ribbon of glass along the laser cut line and applying a heat source to the glass sheet separated from the continuous ribbon of glass at the laser cut line to smooth or round the glass sheet. 
     
     
         42 . The method of  claim 1 , further comprising separating a glass sheet from the continuous ribbon of glass along the laser cut line, followed by cooling the glass sheet to a temperature below a strain point of the glass sheet with a controlled temperature profile. 
     
     
         43 . The method of  claim 1 , wherein laser cutting is performed at or near a top of the continuous ribbon of glass drawn from the draw tower. 
     
     
         44 . The method of  claim 1 , wherein laser cutting is performed at or near a bottom of the continuous ribbon of glass drawn from the draw tower. 
     
     
         45 . The method of  claim 1 , wherein the pulsed laser beam is produced in a pulse burst of two or more individual pulses that decays in intensity over a time of the pulse burst such that a first pulse of the pulse burst of two or more individual pulses has a greater intensity than a second subsequent pulse of the pulse burst of two or more individual pulses. 
     
     
         46 . The method of  claim 45 , wherein the pulse burst exponentially decays in intensity over the time of the pulse burst. 
     
     
         47 . A glass article prepared by a method of laser cutting a continuous ribbon of glass drawn from a draw tower, the method comprising:
 drawing the continuous ribbon of glass from the draw tower; and   laser cutting the continuous ribbon of glass drawn from the draw tower by forming a series of defect lines along a laser cut line, wherein:
 each defect line of the series of defect lines extends through an entire thickness of the continuous ribbon of glass, and 
 each defect line of the series of defect lines is formed by focusing a pulsed laser beam into a laser beam focal line oriented along a beam propagation direction and directed into the continuous ribbon of glass, the laser beam focal line generating an induced absorption within a material of the continuous ribbon of glass such that the induced absorption produces the defect line along the laser beam focal line within the continuous ribbon of glass. 
   
     
     
         48 . A glass article comprising alkaline earth boro-aluminosilicate glass composite including at least one edge having a plurality of defect lines extending at least 250 microns, and each defect line of the plurality of defect lines have a diameter less than or equal to about 5 microns. 
     
     
         49 . The glass article of  claim 48 , wherein a spacing of each adjacent defect line of the plurality of defect lines is from 0.1 micron to 20 microns. 
     
     
         50 . The glass article of  claim 48 , wherein the at least one edge is a separated edge has an Ra surface roughness of less than or equal to about 0.5 micron. 
     
     
         51 . The glass article of  claim 48 , wherein the at least one edge has subsurface damage up to a depth less than or equal to about 100 microns. 
     
     
         52 . The glass article of  claim 48 , wherein a distance between each adjacent defect line of the plurality of defect lines is less than or equal to about 20 microns. 
     
     
         53 . The glass article of  claim 48 , further comprising a thickness of about 10 microns to about 5 mm. 
     
     
         54 . The glass article of  claim 48 , wherein each adjacent defect line of the plurality of defect lines extends a full thickness of the at least one edge. 
     
     
         55 . The glass article of  claim 48 , wherein the at least one edge has subsurface damage up to a depth less than or equal to about 75 microns.