FIELD

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/022394 filed on July 09, 2014 the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

[0002] The present disclosure relates generally to methods for separating a glass sheet and, more particularly, to methods for separating a thin glass sheet.

[0003] Glass sheets are commonly used, for example, in display applications such as, for example, liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), or the like. Sometimes, a glass sheet is separated into multiple sub-sheets which can each be removed from the glass sheet to be used in a particular application.

[0004] Cutting of glass sheets is conventionally accomplished by using mechanical tools. Typically, the glass sheet is first scored, for example, by using a scoring tool (e.g. a sharp carbide wheel for example) that creates a score, or median crack, in the glass sheet, and incidentally, substantial damage to the glass sheet at the cut edge. However, alternative processes exist that use C0 ₂ laser radiation to heat the glass sheet and create tensile stress via a temperature gradient to produce a score. During laser scoring, an initiation defect is formed on the glass sheet to generate a median crack (also known as a partial vent or, simply, a vent). The vent is then propagated by a laser light formed into a beam that traverses across the surface of the glass sheet followed by a cooling area produced by a cooling nozzle. Heating of the glass sheet with a laser beam and quenching it immediately thereafter with a coolant creates a thermal gradient and a corresponding stress field that is responsible for the propagation of the vent. When the score is completed, bending or shear stress is then applied to the glass sheet that causes the vent to complete its propagation through the thickness of the sheet.

[0005] Although the laser scoring technique described above may be less damaging than mechanical scoring processes, the laser scoring process still generates damage to the glass sheet, e.g., particularly during the mechanical separation process involving the applied bending or shear stress. This potentially produces differences in edge strengths when the laser-incident side is evaluated in tensile versus compressive stress. Moreover, for both laser and mechanical scoring techniques, separation of the glass sheet requires at least two steps consisting of creating a score, and then applying a stress to the glass sheet (e.g. a bending stress) to separate the sheet along the score line. Furthermore, the scoring techniques typically generate debris, which can potentially contaminate the sub-sheets. Accordingly, it would be beneficial to provide a simplified separation process that can provide sub-sheets with minimal edge damage and contamination from debris generated in the separation process.

SUMMARY

[0006] There are set forth methods for separating a glass sheet that can provide a simplified separation process and can further provide sub-sheets with minimal edge damage and contamination from debris generated in the separation process.

[0007] In a first aspect, a method of separating a glass sheet comprises the step (I) of providing a glass sheet including a first major surface and a second major surface opposing the first major surface. A layer of adhesive material bonds the second major surface of the glass sheet to a support surface of a carrier substrate. A thickness between the first major surface and the second major surface of the glass sheet is equal to or less than about 300 μιη. The method further includes the step (II) of providing a first defect in the glass sheet; and the step (III) of separating the glass sheet into a plurality of sub- sheets. Step (III) is carried out by traversing a beam of electromagnetic radiation over the first major surface along a first predetermined path to (a) transform the first defect into a first full body crack intersecting the first major surface and the second major surface of the glass sheet; and (b) propagate the first full body crack along the first predetermined path, thereby producing a full body separation of the glass sheet along the first predetermined path while the second major surface of the glass sheet remains bonded to the support surface of the carrier substrate.

[0008] In one example of the first aspect, step (II) further comprises providing a second defect in the glass sheet, and step (III) of separating the glass sheet into a plurality of sub-sheets further comprises traversing a beam of electromagnetic radiation over the first major surface along a second predetermined path to: (a) transform the second defect into a second full body crack intersecting the first major surface and the second major surface of the glass sheet; and (b) propagate the second full body crack along the second predetermined path, thereby producing a full body separation of the glass sheet along the second predetermined path while the second major surface of the glass sheet remains bonded to the support surface of the carrier substrate. In one example, the second predetermined path may intersect the first predetermined path.

[0009] In another example of the first aspect, the method further comprises the step (IV) of releasing at least a portion of at least one sub-sheet from the carrier substrate by producing a curvature in at least one of the second major surface of the glass sheet and the support surface of the carrier substrate. In one example, the step (IV) may comprise completely releasing at least one of the sub-sheets from the carrier glass while maintaining the curvature. In another example, the step (IV) may comprise producing a double bend curvature in the second major surface of the glass sheet by lifting an edge portion of one of the plurality of sub-sheets away from the carrier glass.

[0010] In yet another example of the first aspect, the method further comprises the step (IV) of providing a second defect in the carrier substrate; and the step (V) of separating the carrier substrate into a plurality of sub-carrier substrates by traversing a beam of electromagnetic radiation relative to the carrier substrate along a second predetermined path. In one example, the first predetermined path may be aligned with the second predetermined path. In another example, traversing the laser beam in step (V) may produce a scribe line in the carrier substrate along the second predetermined path. In one particular example, step (V) may further apply a bending force to the carrier substrate to separate the carrier substrate along the scribe line into the plurality of sub-carrier substrates. In still another example, traversing the electromagnetic radiation during step (V) may transform the second defect into a second full body crack extending through the carrier substrate and propagates the second crack along the second predetermined path produces a full body separation of the carrier substrate along the second predetermined path. In another example, each sub-carrier substrate provided by step (V) is bonded with a single corresponding one of the plurality of sub-sheets. In one particular example, the method may further comprise the step (VI) of releasing one of the sub-sheets from the corresponding sub-carrier substrate. [0011] The first aspect may be provided alone or in combination with any one or more of the examples of the first aspect discussed above.

[0012] In a second aspect, a method of separating a glass sheet comprises the step (I) of providing a glass sheet including a first major surface, a second major surface opposing the first major surface, and a thickness between the first major surface and the second major surface equal to or less than about 300 μιη. The second major surface of the glass sheet is bonded to a support surface of a carrier substrate. The method further includes the step (II) of providing a first defect in the glass sheet; and the step (III) of separating the glass sheet into a plurality of sub-sheets. Step (III) is carried out by traversing a beam of electromagnetic radiation over the first major surface along a first predetermined path to (a) transform the first defect into a first full body crack intersecting the first major surface and the second major surface of the glass sheet; and (b) propagate the first full body crack along the first predetermined path, thereby producing a full body separation of the glass sheet along the first predetermined path while the second major surface of the glass sheet remains bonded to the support surface of the carrier substrate. The method further includes the step (IV) of releasing at least a portion of at least one sub-sheet from the carrier substrate by producing a curvature in at least one of the second major surface of the glass sheet and the support surface of the carrier substrate.

[0013] In one example of the second aspect, the step (IV) further comprises completely releasing at least one of the sub-sheets from the carrier glass while maintaining the curvature.

[0014] In another example of the second aspect, the step (IV) comprises producing a double bend curvature in the second major surface of the glass sheet by lifting an edge portion of one of the plurality of sub-sheets away from the carrier glass.

[0015] In yet another example of the second aspect, the step (IV) translates at least a pair of facing edge surfaces of an adjacent pair of sub-sheets away from one another along a direction of the first major surface to create a lateral gap between the pair of facing edge surfaces.

[0016] In still yet another example of the second aspect, step (II) further comprises providing a second defect in the glass sheet, and step (III) of separating the glass sheet into a plurality of sub-sheets further comprises traversing a beam of electromagnetic radiation over the first major surface along a second predetermined path to: (a) transform the second defect into a second full body crack intersecting the first major surface and the second major surface of the glass sheet; and (b) propagate the second full body crack along the second predetermined path. As such, step (III) produces a full body separation of the glass sheet along the second predetermined path while the second major surface of the glass sheet remains bonded to the support surface of the carrier substrate. In one example, the second predetermined path can intersect the first predetermined path.

[0017] In still another example of the second aspect, step (I) includes the step of bonding the second major surface of the glass sheet to the support surface of the carrier substrate with a layer of adhesive material.

[0018] The second aspect may be provided alone or in combination with any one or more of the examples of the second aspect discussed above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other features, aspects and advantages of the present invention are better understood when the following detailed description of the invention is read with reference to the accompanying drawings, in which:

[0020] FIG. 1 is a perspective view of a glass sheet;

[0021] FIG. 2 is a perspective view of the carrier substrate;

[0022] FIG. 3 is a perspective view of the glass sheet bonded to the carrier substrate to form a glass-carrier assembly;

[0023] FIG. 4 illustrates a step of providing first and second defects in the glass sheet;

[0024] FIG. 5 illustrates a step of traversing a beam of electromagnetic radiation over the glass sheet along a first predetermined path;

[0025] FIG. 6 illustrates a full body cut in the glass sheet along the first predetermined path;

[0026] FIG. 7 illustrates an example step of traversing the beam over the glass sheet along a second predetermined path;

[0027] FIG. 8 illustrates a full body cut in the glass sheet along the second predetermined path; [0028] FIG. 9 illustrates an example step of forming a third defect in the carrier substrate;

[0029] FIG. 10 illustrates an example step of traversing the laser over the carrier substrate along a third predetermined path to form a full body crack;

[0030] FIG. 11 illustrates an example step of traversing the laser over the carrier substrate along the third predetermined path to form a partial crack;

[0031] FIG. 12 illustrates the glass-carrier assembly separated into a plurality of sub-assemblies;

[0032] FIG. 13 illustrates the step of releasing a sub-sheet from one of the plurality of sub-assemblies;

[0033] FIG. 14 illustrates the step of producing a curvature in a second major surface of the glass sheet;

[0034] FIG. 15 illustrates the step of producing a curvature in a support surface of the carrier substrate; and

[0035] FIG. 16 is close up view of the glass-carrier assembly during the step illustrated in FIG. 15.

DETAILED DESCRIPTION

[0036] The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments of the claimed invention are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, the claimed invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These example embodiments are provided so that this disclosure will be both thorough and complete, and will fully convey the scope of the claimed invention to those skilled in the art.

[0037] As illustrated in FIG. 1, an example method may comprise providing a glass sheet 10 including a first major surface 12 and a second major surface 14 opposing the first major surface 12. A thickness Tl between the first major surface 12 and the second major surface 14 of the glass sheet 10 can be equal to or less than about 300 μιη, such as equal to or less than about 280 μιη, such as equal to or less than about 230 μιη, such as equal to or less than about 180 μιη, such as equal to or less than about 100 μιη, such as equal to or less than about 50 μηι. The glass sheet 10 can include at least one edge to provide a curvilinear (e.g., oval, circular, etc.) polygonal (e.g., rectangular such as square, etc.) For instance, as illustrated, the glass sheet 10 can further include four edges 16, 18, 20, 22 that define the boundaries of the first major surface 12 that may be arranged in the illustrated square shape although other rectangular shapes may be provided in further examples.

[0038] Turning to FIG. 2, the example method may further comprise providing a carrier substrate 24 that may be provided as a wide range of materials such as glass, ceramic, glass ceramic or other materials. Depending on processing techniques or other requirements, the carrier substrate 24 may or may not transmit light and can therefore be at least partially or entirely transparent, translucent or opaque. The carrier substrate 24 includes a first major surface 26, an opposing second major surface 28, and a thickness T2 between the first and second major surfaces 26, 28. In some examples, the thickness T2 may optionally be greater than or equal to 500 μιη.

[0039] As further illustrated in FIG. 2, the carrier substrate 24 further includes edges 30, 32, 34, 36 that define the boundaries of the second major surface 28. In some examples, the carrier substrate 24 may have a geometrically similar or identical peripheral shape to the glass sheet 10. For example, the illustrated carrier substrate 24 has an outer square shape that can be identical to the outer square shape of the glass sheet 10. In further examples, the carrier substrate 24 may have a shape that, although not identical, is geometrically similar to the shape of the glass sheet 10. For instance, the carrier substrate 24 may have a shape that is slightly larger but geometrically similar to the shape of the glass sheet 10. Providing a larger carrier substrate 24 can help protect the edges of glass sheet 10 from damage. In some examples, the carrier substrate 24 may also have a shape that is substantially larger than the glass sheet 10. In still further examples, the carrier substrate 24 may also have a shape that is smaller than the glass sheet 10.

[0040] As shown in FIG. 3, the second major surface 14 of the glass sheet 10 may be bonded to a support surface (e.g. the first major surface 26) of the carrier substrate 24, thus forming a glass-carrier assembly 42. A layer of adhesive material 40 may be used to bond the second major surface 14 of the glass sheet 10 to the support surface 26 of the carrier substrate 24. Moreover, other bonding techniques such as, for example, hydrogen bonding may be used to bond the second major surface 14 of the glass sheet 10 to the support surface 26 of the carrier substrate 24.

[0041] As can be seen in FIGS. 1-3, the major surfaces 12, 14, 26, 28 of the glass sheet 10 and the carrier substrate 24 are all square in shape and have the same area. However, as mentioned above with respect to the edges, the major surfaces 12, 14, 26, 28 may have different shapes such as, for example, rectangular shapes other than square, curvilinear shapes (e.g., circular, oval, etc.). Moreover, as mentioned previously, the first and second major surfaces 12, 14 of the glass sheet 10 may have a shape or area that varies from the shape or area of the first and second major surfaces 26, 28 of the carrier substrate 24. For example, the first and second major surfaces 26, 28 of the carrier substrate 24 may be rectangular and have a greater area than the square, first and second major surfaces 12, 14 of the glass sheet 10. As such, encounters from external objects may be first encountered by the carrier substrate 24 to thereby protect the edges of the glass substrate 10. Also, the first and second major surfaces 26, 28 of the carrier substrate 24 may be rectangular and have a smaller area than the square, first and second major surfaces 12, 14 of the glass sheet 10.

[0042] The example method can further include providing a first defect 44 and a second defect 46 in the glass sheet 10, as shown in FIG. 4. The first and second defects 44, 46 can be produced using various methods. For example, the first and second defects 44, 46 may be produced by a laser pulse or by a mechanical tool such as a scribe, scoring wheel, diamond tip, indenter, etc. The first and second defects 44, 46 may be formed on any of the edges 16, 18, 20, 22 of the glass sheet 10 or the first and second defects 44, 46 may be formed on the first major surface 12 of the glass sheet 10 away from the edges 16, 18, 20, 22. In the present example, the first defect 44 is formed on the edge 16 of the glass sheet 10 and the second defect 46 is formed on the edge 22 of the glass sheet 10.

[0043] The example method can further include separating the glass sheet 10 into a plurality of sub-sheets. For example, the glass sheet 10 may be separated into a plurality of sub-sheets by traversing a beam of electromagnetic radiation 48 over the first major surface 12 along a first predetermined path 50, as shown in FIG. 5. The first predetermined path 50 in the present example comprises a straight line that extends from the edge 16 of the glass sheet 10 at the location of the first defect 44 to the edge 20 of the glass sheet 10. However, the first predetermined path 50 in other examples may comprise a curve. Moreover, the first predetermined path 50 may extend from the edge 16 of the glass sheet 10 at the location of the first defect 44 to any other edge of the glass sheet 10. Furthermore, the first predetermined path 50 may comprise a closed path that is completely confined within the boundaries of the first major surface 12 such that it does intersect with any edge of the glass sheet 10. The first predetermined path 50 may comprise any path that extends along or across the first major surface 12 of the glass sheet 10.

[0044] A moveable laser irradiation device 52 can be used to produce and translate the beam of electromagnetic radiation 48 along the first predetermined path 50. As the beam 48 is traversed along the first predetermined path 50, a heated region 54 is formed on the first major surface 12. The beam 48 can be followed, optionally, with a cooling device 56 that applies a cooling fluid 58 to the glass sheet 10 along the first predetermined path 50 subsequent to the heating of the beam 48, as further shown in FIG. 5. The cooling fluid 58 can be a liquid or gas or combination of liquid and gas. The application of the cooling fluid 58 produces a cooled region 60 on the first major surface 12 that is substantially lower in temperature than the heated region 54. As a result of this temperature difference, a thermal stress is generated in the glass sheet 10 that causes the first defect 44 to transform into a first full body crack 64 intersecting the first major surface 12 and the second major surface 14 of the glass sheet 10. The first full body crack 64 then propagates along the first predetermined path 50 as the beam 48 and cooling fluid 58 are traversed along the first predetermined path 50. As shown, optionally, the first full body crack 64 may be produced without propagating into the carrier substrate 24. As can be seen in FIG. 6, once the beam 48 and cooling fluid 58 completely traverse the first predetermined path 50, a full body separation of the glass sheet 10 is produced along the first predetermined path 50 from the first major surface 12 to the second major surface 14, thus separating the glass sheet 10 into two sub-sheets 68, 70. Moreover, because the second major surface 14 of the glass sheet 10 remains bonded to the support surface 26 of the carrier substrate 24 during and after separation, the two sub-sheets 68, 70 remain substantially in contact or in close proximity with each other along their line of separation.

[0045] The step of separating the glass sheet 10 into a plurality of sub-sheets may further comprise traversing the beam of electromagnetic radiation 48 over the first major surface 12 along a second predetermined path 78, as shown in FIG. 7. The second predetermined path 78 in the present example comprises a straight line that extends from the edge 22 of the glass sheet 10 at the location of the second defect 46 to the edge 18 of the glass sheet 10. Moreover, as shown, the second predetermined path 78 can intersect with the first predetermined path 50. As shown, the second predetermined path 78 may also be oriented perpendicular to the first predetermined path 50. However, the second predetermined path 78 need not be perpendicular to the first predetermined path 50. Rather, second predetermined path 78 can form any angle with the first predetermined path 50. Moreover, the second predetermined path 78 in some examples may comprise a curve rather than a straight line. Furthermore, the second predetermined path 78 may extend from the edge 22 of the glass sheet 10 at the location of the second defect 46 to any other edge of the glass sheet 10. Still further, the second predetermined path 78 may comprise a closed path that is completely confined within the boundaries of the first major surface 12 such that it does intersect with any edge of the glass sheet 10. The second predetermined path 78 may comprise any path that extends along or across the first major surface 12 of the glass sheet 10 that intersects with the first predetermined path 50.

[0046] As the beam 48 is traversed along the second predetermined path 78, the heated region 54 is once again formed on the first major surface 12. The beam 48 can, optionally, be followed with the cooling device 56 to apply the cooling fluid 58 to the glass sheet 10 along the second predetermined path 78 subsequent to the heating of the beam 48, thus forming the cooled region 60. A thermal stress is generated in the glass sheet 10 that causes the second defect 46 to transform into a second full body crack 82 intersecting the first major surface 12 and the second major surface 14 of the glass sheet 10. The second full body crack 82 then propagates along the second predetermined path 78 as the beam 48 and cooling fluid 58 are traversed along the second predetermined path 78. [0047] As shown, optionally, the second full body crack 82 may be produced without propagating into the carrier substrate 24. Eventually, the second full body crack 82 will propagate along the second predetermined path 78 to the separation line of the two sub-sheets 68, 70. As the two sub-sheets 68, 70 are substantially in contact or in close proximity with each other along their line of separation, the second full body crack 82 will continue to propagate past the separation line of the two sub-sheets 68, 70 without the need of an additional defect. Thus, as can be seen in FIG. 8, once the beam 48 and cooling fluid 58 completely traverse the second predetermined path 78, a full body separation of the glass sheet 10 is produced along the second predetermined path 78 from the first major surface 12 to the second major surface 14, thus separating the glass sheet 10 into four sub-sheets 86, 88, 90, 92. This separation along the second predetermined path 78 can also be referred to as a cross-cut, since the separation along the second predetermined path 78 crosses the separation of the glass sheet 10 along the first predetermined path 50. Because the second major surface 14 of the glass sheet 10 remains bonded to the support surface 26 of the carrier substrate 24 during and after separation, the four sub-sheets 86, 88, 90, 92 remain substantially in contact or in close proximity with each other along the lines of separation. In this example, for sub-sheets 86, 88, 90, 92 were formed requiring half the number or less of initiation defects. As the number of sub-sheets increases, the relative number of required initiation defects decreases.

[0048] Although the example method described thus far separates the glass sheet 10 along two predetermined paths of separation, the method in other examples may separate the glass sheet 10 along any number of predetermined paths of separation. In such examples, a defect can similarly be formed for each predetermined path and the beam 48 and optional cooling fluid 58 may similarly be applied to the glass sheet 10 to transform the defect into a crack and propagate the crack along the corresponding predetermined path. If the predetermined path happens to cross a line of separation between two sub-sheets of the glass sheet 10, the crack will continue to propagate past the line of separation since the sub-sheets would remain in thermal contact due to the bonding of the glass sheet 10 and carrier substrate 24. [0049] Once the glass sheet 10 has been separated into a desired number of sub- sheets, one or more of the sub-sheets may be released from the glass-carrier assembly 42 in a variety of ways. For example, FIGS. 9-13 illustrate one way of releasing one or more of the sub-sheets from the glass-carrier assembly 42. As shown in FIG. 9, after the glass sheet 10 has been separated into the four sub-sheets 86, 88, 90, 92, the method can comprise the step of providing a third defect 102 in the carrier substrate 24. The third defect 102 may be formed on any of the edges 30, 32, 34, 36 of the carrier substrate 24 or the third defect 102 may be formed on the second major surface 28 of the carrier substrate 24 away from the edges 30, 32, 34, 36. For illustrative purposes, third defect 102 is shown formed on the edge 30 of the carrier substrate 24.

[0050] After the third defect 102 has been formed, the carrier substrate 24 may be separated into a plurality of sub-carrier substrates by traversing the beam of electromagnetic radiation 48 relative to the carrier substrate 24 along a third predetermined path 112, as shown in FIG. 10. Preferably, the third predetermined path 112 is aligned with the first predetermined path 50 and comprises a straight line that extends from the edge 30 of the carrier substrate 24 at the location of the third defect 102 to the edge 34 of the carrier substrate 24. However, the third predetermined path 112 may comprise any path that extends across the second major surface 28 of the carrier substrate 24.

[0051] As the beam 48 is traversed along the third predetermined path 112, the heated region 54 is formed on the second major surface 28 of the carrier substrate 24. The beam 48 can be followed with the cooling device 56 to apply the cooling fluid 58 to the carrier substrate 24 along the third predetermined path 112 subsequent to the heating of the beam 48, thus forming the cooled region 60. A thermal stress is generated in the carrier substrate 24 that causes the third defect 102 to transform into a crack 116 that is then propagated along the third predetermined path 112 as the beam 48 and the cooling fluid 58 are traversed. In the present embodiment, the crack 116 is a full body crack that extends through the entire thickness T2 of the carrier substrate 24, thus producing a full body separation of the carrier substrate 24 along the third predetermined path 112. However, in other embodiments, the crack 116 may be a partial crack that propagates only partially through the thickness T2 of the carrier substrate 24, thus forming a scribe line 118 along the third predetermined path 112, as shown in FIG. 11. In such embodiments, a bending force may be subsequently applied to the carrier substrate 24 to then separate the carrier substrate 24 along the formed scribe line 118 into a plurality of sub-carrier substrates. Besides use of electromagnetic radiation, the carrier substrate 24 can also be separated by use of mechanical scribing or other methods. The methods to separate the carrier substrate 24 and the glass sheet 10 are not required to be the same.

[0052] The carrier substrate 24 may be separated into any number of sub-carrier substrates using the scribe and/or full body cut techniques described above. For example, FIG. 12 shows the glass-carrier assembly 42 after the carrier substrate 24 has been separated along two predetermined paths aligned with the first and second predetermined paths 50, 78 that the glass sheet 10 was separated along. As can be seen, the carrier substrate 24 has been separated into the four sub-carrier substrates 120, 122, 124, 126. Consequently, the glass-carrier assembly 42 is separated into the four sub-assemblies 130, 132, 134, 136, wherein each sub-carrier substrate 120, 122, 124, 126 is bonded with a single corresponding one of the plurality of sub-sheets 86, 88, 90, 92 to form one of the four sub-assemblies 130, 132, 134, 136. Each of these sub-assemblies 130, 132, 134, 136 may be used for separate applications. Moreover, because each sub-sheet 86, 88, 90, 92 is part of a separate sub-assembly 130, 132, 134, 136, each sub-sheet 86, 88, 90, 92 may be released from its corresponding sub-carrier substrate 120, 122, 124, 126 without the risk of bringing edges of the sub-sheet into contact with the remaining sub-sheets that may otherwise damage the edges. For example, FIG. 13 shows the step of releasing sub-sheet 86 of sub-assembly 130 from the sub-carrier substrate 120. The sub-assembly 130 has been isolated from the remaining sub-assemblies 132, 134, 136. As such, the sub-sheet 86 may be released without the risk of bringing edges of the sub-sheet 86 into contact with the remaining sub-sheets 88, 90, 92.

[0053] Although the releasing steps described above involve separating the carrier substrate 24 into a plurality of sub-carriers after the glass sheet 10 has been separated, the releasing steps in other examples may separate the carrier substrate 24 into a plurality of sub-carriers before the glass sheet 10 is separated. Moreover, in other examples, scribe lines may be first formed in the carrier substrate 24, followed by the separation of the glass sheet 10, and then the bending stress can be applied to the carrier substrate 24 to separate the carrier substrate 24 along the scribe lines and into a plurality of sub-carriers.

[0054] FIGS. 14-16 illustrate alternative steps of releasing one or more of the sub-sheets from the glass-carrier assembly 42 that do not include separating the carrier substrate 24 into sub-carrier substrates. For example, after the glass sheet 10 of the glass- carrier assembly 42 has been separated into a plurality of sub-sheets, the method can comprise the step of releasing at least a portion of at least one sub-sheet from the carrier substrate 24 by producing a curvature in at least one of the second major surface 14 of the glass sheet 10 and the support surface 26 of the carrier substrate 24. For instance, FIGS. 14 and 15 show the glass-carrier assembly 42 after the glass sheet 10 has been separated into four sub-sheets 86, 88, 90, 92. As shown in FIG. 14, a double bend curvature can be produced in the second major surface 14 of the glass sheet 10 by lifting an edge portion 142 of one of the plurality of sub-sheets 86 away from the carrier substrate 24. In just one example, the edge portion 142 may be lifted away such that facing edge surfaces 144, 146 of adjacent sub-sheets 86, 92 immediately begin moving away from one another while the edge portion 142 is lifted away. For instance, in one example, the double bend curvature allows the facing edge surfaces 144, 146 to be maintained substantially parallel with each other while the edge portion 142 is lifted away. As the facing edge surfaces remain substantially parallel, the facing edge surfaces 144, 146 can begin immediately moving away from one another as the edge portion 142 is lifted away. However, there may be embodiments wherein the facing edge surfaces 144, 146 are slightly non-parallel while the edge portion 142 is lifted away. The double bend curvature permits the edge surfaces 144, 146 to remain substantially parallel or slightly non-parallel while the edge portion 142 is lifted away to peel the sub-sheet 86 away from the carrier substrate 24. By lifting the edge portion 142 away from the carrier substrate 24 in this manner, edges 150, 152 of the sub-sheet 86 are prevented from rubbing against the edge surface 146. As such, damage to the edge surface 146 can be avoided that may otherwise occur with other releasing techniques. The sub-sheet 86 may be completely released from the carrier substrate 24 while maintaining this double bend curvature. However, there may be embodiments wherein the double bend curvature is maintained only while a portion of the sub-sheet 86 is being released from the carrier substrate 24. Also, the sub-sheet 86 can optionally be released from the carrier substrate 24 using other single -bend geometries, as well, and geometries that release the sub-sheet 86 starting from the exterior edge instead of the interior edge surface 144 as shown in FIG. 14.

[0055] Turning to FIGS. 15 & 16, in still another example, a curvature may be produced in the support surface 26 of the carrier substrate 24 to release at least a portion of the sub-sheet 86 from the carrier substrate 24. As can be seen in FIGS. 15 & 16, producing the curvature translates the pair of facing edge surfaces 144, 146 of the adjacent pair of sub-sheets 86, 92 away from one another along a direction D of the first major surface 12 to create a lateral gap 156 between the pair of facing edge surfaces 144, 146. The presence of the gap 156 can prevent the edges 150, 152 of the sub-sheet 86 from rubbing against the edge surface 146 as the edge portion 142 of the sub-sheet 86 is lifted away from the carrier substrate 24. Moreover, a double or single bend curvature can be further produced in the second major surface 14 of the glass sheet 10 while lifting the edge portion 142 away from the carrier substrate 24 to help further prevent the edges 150, 152 of the sub-sheet 86 from rubbing against the edge surface 146 as the edge portion 142 of the sub-sheet 86 is lifted away. The sub-sheet 86 may be completely released from the carrier substrate 24 while maintaining the curvature in the support surface 26 of the carrier substrate 24. However, there may be embodiments wherein the curvature in the support surface 26 of the carrier substrate 24 is maintained only while a portion of the sub-sheet 86 is being released from the carrier substrate 24.

[0056] Although FIGS. 14-16 illustrate steps of releasing one or more of the sub- sheets from the glass-carrier assembly 42 that do not include separating the carrier substrate 24 into sub-carrier substrates, there may be embodiments wherein one or more of the sub-sheets are released from the glass-carrier assembly 42 that include both separating the carrier substrate 24 into sub-carrier substrates and producing a curvature in at least one of the second major surface 14 of the glass sheet 10 and the support surface 26 of the carrier substrate 24 as described above. For example, after the glass sheet 10 of the glass-carrier assembly 42 has been separated into four sub-sheets 86, 88, 90, 92, the carrier substrate 24 may be separated along a single predetermined path to produce two sub-assemblies that each comprise two sub-sheets bonded to a sub-carrier. A curvature may then be produced in at least one of the second major surface 14 of the glass sheet 10 and the support surface 26 of the carrier substrate 24 to remove one of the sub-sheets from one of the sub-assemblies.

[0057] The example method described above can provide a number of advantages over typical laser scoring techniques. For instance, typical laser scoring techniques for glass sheets require at least two steps consisting of creating a score, and then applying a stress to the glass sheet to separate the sheet along the score line. Also, mechanical defects may occur during the mechanical separation process involving the applied bending or shear stress. This potentially produces differences in edge strengths when the laser-incident side is evaluated in tensile versus compressive stress. However, the method described above simplifies the separation process by creating full body cracks 64, 82 in the glass sheet 10 that separate the glass sheet 10 without the need for an additional step of applying a stress to the glass sheet 10. As another advantage, the method described above minimizes the amount of edge damage produced during cross-cutting applications that have intersecting lines of separation. Because the glass sheet 10 in the example method is bonded (e.g., with adhesive) to the carrier substrate 24, any sub-sheets formed will remain substantially in contact or in close proximity with each other along their lines of separation. Thus, if any cracks are propagated across an existing line of separation, it is not necessary to produce another edge defect to continue propagation of the crack across the line. Indeed, as can be seen in FIG. 8, the sub-sheet 90 was formed without the need to create any edge defects along its perimeter. As yet another advantage, the method described above can help prevent edge damage to the glass sub-sheets that can occur while they are being removed from the carrier substrate 24 by separating the glass-carrier assembly 42 into a plurality of isolated sub-assemblies that each have a single sub-sheet or by producing a curvature in at least one of the second major surface 14 of the glass sheet 10 and the support surface 26 of the carrier substrate 24.

[0058] Examples will now be described of experiments that the inventors conducted using the method described above.

EXAMPLE 1

[0059] In one example, a glass sheet comprising Corning® Willow® Glass (available from Corning Incorporated, Corning, NY) and having a thickness of 130 um was bonded to a carrier glass substrate comprising Corning® EAGLE XG® Glass (available from Corning Incorporated, Corning, NY) and having a thickness of 700 μιη. The carrier glass substrate was coated with plasma polymerized teflon (-PPT) to facilitate bonding and debonding. Defects were then generated in an edge region of the glass sheet using a diamond tip or a scoring wheel. Afterwards, C0 ₂ laser cross-cutting of the glass sheet was carried out using a 400 W RF-excited C0 ₂ laser. The laser beam was expanded and focused using an asymmetrical aspheric lens to produce a rectangular footprint on the surface of the glass sheet having a dimension of roughly 45 mm long and 1.5 wide. The laser beam had a top-hat intensity profile on both its long (45 mm) and short (1.5 mm) axis. Cutting was carried out along the long axes of the footprint. A mist jet followed the laser beam to quench the glass sheet using de-ionized water as a coolant. The laser beam and mist jet were operated under the following conditions during the cross-cutting:

Laser power: 160 W

Water flow: 10 seem

Air Flow: 3 1pm

Cutting speed: 250 mm

[0060] A first cut was made with the C0 ₂ laser followed by a second cut that intersected the first cut. Full-body cracks were observed for both the first and second cuts. The second cut was observed to propagate through the first cut without hindrance. Glass sub-sheets produced by the cross-cutting process above were extracted with ease from the carrier substrate.

EXAMPLE 2

[0061] In another example, a glass sheet comprising Corning® Willow® Glass was bonded to a carrier glass substrate comprising Corning® EAGLE XG® Glass to produce a glass-carrier assembly. The carrier glass substrate was coated with PPT to facilitate bonding and debonding. Defects were then generated in edge regions of both the glass sheet and carrier substrate using a diamond tip or a scoring wheel. The glass sheet was cut using the same parameters described in Example 1. However, prior to cutting, a scribe line was formed on the carrier substrate using the laser beam. A bending stress was then applied to the glass-carrier assembly to propagate the crack of the scribe line and break the carrier glass along the scribe line. The crack did not propagate into the glass sheet. A full-body crack was subsequently initiated in the glass sheet and propagated to separate the glass sheet.

EXAMPLE 3

[0062] In another example, a glass sheet comprising Corning® Willow® Glass was bonded to a carrier glass substrate comprising Corning® EAGLE XG® Glass to produce a glass-carrier assembly. The carrier glass substrate was coated with PPT to facilitate bonding and debonding. Defects were then generated in an edge region of the glass sheet using a diamond tip or a scoring wheel. The glass sheet was then cut using the same parameters described in Example 1. Afterwards, a laser cross-scribe process was carried out on the carrier glass substrate. The laser scribe lines were carefully aligned with cuts on the glass sheet. A bending stress was then applied to the glass-carrier assembly to break the carrier glass along the scribe lines.

[0063] It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.